My Planetary Nebula candidates

Pre 1

Coordinates: 20 27 35.50 +10 28 10.40 (J2000.0)

This is a small annular object in the Delphinus constellation, rather elliptical in morphology. It was found when hunting for Planetary Nebula candidates in the Digitalized Sky Survey (DSS) plates, via Aladin Lite.  Despite most likely being a galaxy, Pre 1 remains my first Planetary Nebula (PN) candidate discovery. Only acquiring a spectra for this object can truly confirm nature of this object.Pre 1 discovery imagesDiscovery image of Pre 1. Notice it’s obvious elongated and annular nature.Credit: DSS2 Aladin Lite.

Before finding  Pre 1, I had been hunting the DSS plates for a few months in search for previously unknown/uncatalogued deep sky objects. I had already stumbled on some occasional asterisms, but I had yet to find an unknown Planetary Nebula candidate.

In Mid-December, 2015 while reading archive messages posted on the Deep Sky Hunters Yahoo forum, I came accross an interesting message posted by PN hunter, Dana Patchick on February 18th, 2012. The message was regarding a Possible PN Dana had found in DSS, a bright one that had gone unnoticed until he found it in February 6th, 2012. The object is currently named Pa 15 (aka the “Little blue fox”) and is a compact, blue PN in Vulpecula. Pa 15DSS2 image extract showing Pa 15 as a compact quasi-stellar blue nebula. Image credit: DSS2 Aladin Lite.

Knowing that such nice and obvious PNe could still be found, It motivated me to again hunt for PNe! From Pa 15 in Vulpecula, I scrolled southward through the DSS2 plates via Aladin Lite, towards the Delphinus constellation. After 2 hours of hunting, I finally noticed an uncatalogued annular object located between a few stars. The general morphology of the object was what one could expect from a PN. Furthermore, the object appeared alot fainter in the near-Infrared images from DSS and 2MASS, which is typical of PNe. Despite not being quite as bright and ovious as Pa 15, it was certainly a well defined nebulous object, and it deserved some follow-up! 🙂 Pre 1 DSS filtersPre 1 as seen in the different DSS plates. The nebula seems absent in the IR filter, while apparent in both the optical plates (typical behavior of a PN). However, rather than the object actually being faint in the NIR, the observed effect could be due to the sensitivity of the image itself (notice how the brightness of all the field stars vary similarly between the different filters). Credit: SuperCosmos Sky Survey.

After sending an e-mail to PN hunter, Pascal Le Dû (Brittany, France), he mentioned that its signal in the WISE W4 band was stronger that in the other WISE filters, which was also a good sign in favor of a PN. Astronomer Agnès Acker, agreed that these characteristics were enough to classify it as a “Possible Planetary Nebula” candidate. It was informally designated Pre 1 in early 2016. However, it was suspected that it could instead be a possible annular galaxy of some sort, as galaxies tend to occasionally mimic PNe in DSS, and sometimes even in WISE. The lack of data for this object made it a difficult object to classify.

In late 2016, the Pan-STARRS1 dataset was made available to the public. Pan-STARRS1 is made up of 5 seperate filters, covering Optical and near-IR wavelengths. Furthermore, its resolution is alot higher than that of the DSS plates. Because of these properties, it’s an efficient tool to distinguish between Galaxies and PNe.  Pan-STARRS images showed that the object was brighter in the near-IR images than the DSS IR plate suggested. As Dana Patchick told me, the DSS2-IR plates are not always reliable. Galaxies often appear well in the near-IR. The morphology also seems to be more in favor of a galaxy.

Pre 1 panstarrsExtract from Pan-STARRS1 (g + r + i) shows Pre 1 to be more likely a galaxy than an actual Planetary Nebula. Credit: Pan-STARRS1 Science Consortium.


Pre 2, Pre 5, Pre 24, Pre 29

Similarly to Pre 1, these four PN candidates could infact be galaxies. Both Pre 5 and Pre 24 appear to have to have the colours of a galaxy in Pan-STARRS1 images. Pre 2 and Pre 29 are located outside the FOV of Pan-STARRS1, as well as that of the SDSS and UKST/Halpha, making them difficult to classify. Looking at the morphology of Pre 2, it seems like it could be a faint face-on spiral galaxy overlaped by a foreground star. Pre 29 could be a faint dwarf galaxy, as the surrounding field contains quite a few galaxies. All these objects were found in DSS2 images via Aladin Lite.

PNe Pre candidates galaxies

Discovery DSS2 images of Pre 2, Pre 5, Pre 24 and Pre 29. Image credit: DSS2 Aladin Lite.


Pre 3 – Southern Soccer Ball Nebula

This is a circular nebula Planetary Nebula candidate in the Centaurus constellation. Amateur and professional narrow-band images of this nebula have revealed internal structures similar to the well-known “Soccer Ball Nebula” in Cygnus, hence its name. This is perhaps my first reliable Planetary Nebula candidate.

Pre 3 discovery image

Discovery image of Pre 3. Credit: DSS2 Aladin Lite.

I found this object using Aladin Lite’s DSS2 images, after scrolling through the Centaurus constellation for some interesting asterisms or possible PN candidates. It appeared as a very faint blue homogenous disk, a bit more contrasted on its SW edge. It had a centered blue star that appeared very bright in the GALEX Ultraviolet images. It looked very much like a circular Planetary Nebula. Dana Patchick found the nebula to appear in WISE, only in the W4 band, which was a good sign.

In March, 2016, astrophotographer Steve Crouch imaged this faint nebula in OIII and Halpha filters. Not only did his images support the PN classification, but they revealed structures in OIII that could not be visible in the DSS plates.

Pre 3 image extract steve crouch.bmp

Extract of Steve Crouch’s image of Pre 3 taken in March 2016. Filters: Halpha +OIII +RGB.

In 2017, images were acquired by professional astronomer George Jacoby from the Las Campanas Observatory in Chile. This was done along with the help of Matthias Kronberger and Dana Patchick. The images showed the OIII structures to be very similar to those seen in the “Soccer Ball Nebula”, which lead them to officially name the object the “Southern Soccer Ball”. Amateur astronomer Kent Wallace also noticed the striking similarities via his own observations.

pre 3 lcoExtract of the Image (OIII + Halpha) taken by the 1 meter telescope at Las Campanas Observatory in Chile. Image credit: George Jacoby/LCO. Image combined and enhanced by Dana Patchick.


Pre 4

Pre 4 was found at the end of March, 2016, and is my first Planetary Nebula candidate discovered using AllWISE imagery (W1+W2+W4). While the object is bright in the Mid-IR (like most compact PNe), the nebula has much weaker optical emissions. In fact, the nebula is hardly detectable in the DSS Red plates, while practically absent in the SHS Short Red images. Only DECaPS and SHS Halpha red plates seem to show the object clearly, due to the high resolution of the former, and the strong Halpha emission of the PN in the latter case. The nebula is also visible in Spitzer, displaying the typical “PN green” appearance in the Aladin Lite images.

Pre4_AllWISEDiscovery AllWISE image of Pre 4. The nebula appears as a bright spot in the W4 band (colour coded red), in comparison to most stars that emit much more significantly in the Mid-IR (W1 and W2 filters). Image credit: Aladin Lite AllWISE

The faint nature of Pre 4 is partially due to the significant magnitude extinction at its location. The effects of interstellar reddening are also clearly apparent in the DECaPS image extract, where the nebula appears rather “yellow” than “green”.  When I first noticed the PN, I believed the nebula could be 10″ in diameter, based on my observations of the DSS2 Red Plate. Indeed, the relatively poor resolution of the DSS plates has caused the PN to mix with that of many faint surrounding stars, leading to a nebulous patch of 10″. Dana Patchick was the first to point out the correct dimenshions based on the SHS Halpha plates (about 4.5″). In SHS Halpha the object is very compact, but still clearly neboulous.

Pre_4_DSS_SHSPre 4 as seen in a DSS2 Red plate extract, as well as in the SHS short red and Halpha filters. While there might be traces of Pre 4 in DSS2 Red, these are mixed with surrounding stars, leading to a 10″ poorly resolved “cluster”, ressembing that of a true nebula. The PN itself is much smaller, as the SHS Halpha shows.

DECaPS clearly shows the nebulosity of the object, even indicating that it might have a bipolar morphology. Even higher resolution observations will be needed to confirm these observations.

Pre_4_DECaPSDECaPS image extract of Pre 4. More than being clearly detectable in this image, the high resolution shows the nebulosity very well, even indicating that the morphology might be bipolar. Image credit: Aladin Lite DECaPS


Pre 8

This is a faint circular Planetary Nebula in the Pisces constellation. It was found when looking at an asterisms nearby found by Khadija El Kanbi, using the available DSS2 plates via Aladin Lite.  Spectra of this nebula was taken from Astroqueyras Observatory (France) which confirmed the object to be a true PN.

SDSS and DSS Pre 8

Discovery DSS2 image and SDSS image of Pre 8. The images have been enhanced to better distinguish the nebula. Image credit: DSS2 and SDSS Aladin Lite.

The nebula also emits weakly in the mid-IR. In WISE it appears faintly and nebulous in the W4 band. This is common for PNe. The nebula is associated with a blue central star, that appears very bright in GALEX UV data.

Just after having been reported, Dana Patchick suggested the possibility of a  6.5′ diameter Halo surrounding Pre 8, based on DSS2 images. Unfortunately Narrow-Band images has proven this external nebulosity to be “well-shaped” background dust.

Karel Teuwen (Belgium) and Stephane Zoll (France) were the first to image this object in narrow-band Halpha and OIII filters. Their images showed the nebula to be brightest in OIII images, alot brighter than its appearance in DSS and SDSS images.

Stephane Zoll Pre 8

Extracts pf the Narrow-band images of Pre 8 taken by Stephane Zoll. The nebula appears brightest in OIII images. Image credit: Stephane Zoll.

In August 2016, Pascal Le Dû was able to obtain a spectra from Astroqueyras observatory, France. Soon after a spectra was taken by George Jacoby et al at the NOAO. Both spectrae show that Pre 8 has emissions in the OIII and Halpha bands, especially in the OIII band like the amateur images suggested. The spectrae confirm the object to be a PN!


Confirmation sepctra of Pre 8 taken by Pascal Le Dû from Astroqueyras Observatory. The spectra confirms Pre 8 being a Planetary Nebula.

Image2Second confirmation spectra of Pre 8 taken by Dr. Jacoby et al. in late 2016. Image credit: Dr Jacoby NOAO IRAF.

Despite being a faint, several sightings of this objects have been reported by amateur astronomers, including Matthias Kronberger. According to him this object is an interesting target for amateurs with large equipment.

In late-2017, The Kitt Peak National Observatory (KPNO) in Arizona took OIII and Halpha high-resolution exposures of shot of Pre 8. These are yet the highest resolution images of this faint PN.

Pre 8 KPNOPlanetary Nebula Pre 8 as images by the KPNO (Kitt Peak National Observatory) in OIII and Halpha filters. Image credit: Di Harmer from KPNO with the 4-m Mayall (H-alpha + [O III] + [O III])


Pre 9

This small Planetary Nebula candidate was found using the AllWISE images on Aladin Lite. In WISE it consists of a Mid-IR source only visible in the WISE W3 and W4 bands. In DSS it appears as a small compact nebula, visible only in the Optical DSS plates. It appears very bright in the UKST Halpha images. Pan-STARRS1 images reveal the nebula to have an elliptical morphology.

Pre 9 panstarrs

Pre 9 as seen in Pan-STARRS1 (g + r + i) images. Image crredit: Pan-STARRS1 Science Consortium.

Pre 11

This is a small Planetary Nebula candidate I found when searching AllWISE images and the SHS Halpha images for previously unknown PNe. I first noticed it in AllWISE as an object that appeared very well in its W3 and W4 filters, but rather stellar in DSS2. It also appeared badly in Halpha images as those were contaminated by IC 2984. Knowing that this was a highly photographed area by astrophotographers, I decided to search narrow-band SHO images of the object. I then noticed the APO team had just recently taken a very detailed long-exposure of the field. Lucky I was! The object had the tint of a Planetary Nebula in those images, (*very* slightly) fuzzy according to their images. This information was enough for it to be kept as a potential PN candidate.

SHO Pre 11Recovery image of Pre 11. This is a composite SII+Halpha+OIII (SHO) image of the Prawn nebula in Scorpius. Notice the green tint of Pre 11 as seen in these images, a typical property of Planetary Nebula. (c) APO Team

In early-2018, the DECaLS  Data Relase (DR1) was made public. In those images Pre 11 appeared very well, as a small elliptical nebula, even more in favour of the PN nature of the object!

Pre 11 DeCalCombined DECaLS image extract combination of the  g, r and z filters showing Pre 11. Notice its apparent elliptical nature in these images. Image credit: Aladin Lite DECaLS.

Pre 13

This Probable Planetary Nebula was found using the AllWISE images from Aladin lite. In these images it appeared as a bright Mid-IR source mainly visible in the WISE W3 and W4 bands. In the Aladin Lite DSS2 images it looks alot like a galaxy. The latter is supported by the numerous other galaxies in the surrounding field.

AllWISE Pre 13

Discovery AllWISE image and the DSS2 (Red+Blue) image from Aladin Lite. Notice how it appears like a galaxy in DSS2.

Unlike the other nearby galaxies, Pre 13 appeared alot fainter in the DSS IR plate in comparison to the optical ones. Furthermore, it was completely absent in the 2MASS images. I decided to report this object to Agnès Acker and Pascal Le Dû as it might be added to their list of “Non-Planetary Nebula candidates”. Because of the IR signals, it was deemed a possible PN candidates, but also as a possible galaxy.

Pre 13 dss

Pre 13 seen in the different DSS bands. Image credit: SuperCosmos Sky Survey.

In May-June, 2017 images were taken from Las Campanas Observatory in Chile by astronomer George Jacoby. The images proved that Pre 13 was not a galaxy, but a likely bipolar Planetary Nebula.

Pre 13 Ha+OIII+OIII RGB (1)

Image (OIII + Halpha) taken by the 1 meter telescope at Las Campanas Observatory in Chile. Image credit: George Jacoby/LCO. Image combined by Dana Patchick.


Pre 12, Pre 15, Pre 17, Pre 18

These are four faint PN candidates that I found in 2016 when hunting the AllWISE and SHS Halpha images. Pre 12 and Pre 18 appear rather amorphous in SHS Halpha images while Pre 15 and Pre 17 appear round (and even clearly elliptical in the case of Pre 17!). Both Pre 12 and Pre 17 are visible in DECaPS data, while Pre 15 is also visible in SDSS, and Pre 18 in DSS Red.

Pre 12 15 17 18SHS Halpha, SDSS and DECaPS image extracts of Pre 12, Pre 15, Pre 17 and Pre 18. Notice the obvious elliptical nature of Pre 17. Image credit: DECaPS and SDSS Aladin Lite, and the SuperCosmos Halpha Survey.


Pre 16

This is a very faint Planetary Nebula candidate. I found it in a composite SHS Short Red + Halpha image centered on PN G002.3+06.5 from the MASH-I site. I first thought the object to be an artefact, until I realized it was correlated to a PN-like WISE signal! The nebula is also very weakly detectable in Pan-STARRS1 data (only visible after heavy processing!)

Pre 16Image to the left: Cropped SHS image that was initially centered on PN G002.3+06.5 (upper center). This was the discovery image of Pre 16 (lower left). Image to the right: Heavily processed Pan-STARRS1 g image extract showing Pre 16 covering the central region of this image. The shape is similar to what observed in SHS.


Pre 19 and Pre 20

These were to Planetary Nebula candidates I found when searching the surroundings of the Carina Nebula (NGC 3372) for previously unknown PNe. In this particular case, I combined the use of WISE and narrow-band images taken by APO.

Pre 19 20 DGPExtract of the discovery APO SHO image of Pre 19 and Pre 20. The nebulae can be seen displaying a particular blue and blue-green tint that doesn’t match up with its surroundings. (c) APO team.

Pre 19 appears quasi-stellar in DSS and SHS plates, but has an obvious bipolar nature in DECaLS images. Pre 20 in comparison is nebulous in DSS, SHS, appearing as an obvious elliptical nebula in DECaLS images! Pre 20 is also visible in a NOAO image of the Carina Nebula where it also displays a nebulous nature.

Pre 19 Pre 20 decalsDECaLS image extracts showing Pre 19 and Pre 20. Notice their obvious bipolar and elliptical nature respectively. Image credit: DECaLS Aladin Lite.


Pre 7, Pre 22, Pre 27 and Pre 28

These are small round nebulae located found when searching AllWISE, DSS and SHS Halpha data. Pre 7 is one of the few PN candidates I found located in the Northern Hemisphere (Cygnus). It appears elliptical in DSS and IPHAS images. Pre 22 also appears elliptical (in DECaPS and SHS Halpha images). Pre 27 is very faint strongly obscured PN candidate with an elongated signal in SHS Halpha. Pre 28 is an object with a disk-like WISE W4 signal, appearing very well in SHS Halpha images, and blue in DSS2 images. The central star of this nebula is not typical of a white dwarf star however.

Pre 7 22 27 28SHS Halpha, IPHAS and DECaPS image extract of Pre 7, Pre 22, Pre 27 and Pre 28. Notice the obvious blue colour and elliptical morphology of Pre 22. Image credit: DECaPS Aladin Lite, SuperCosmos Sky Survey and IPHAS.


Pre 30

Coordinates: 18 34 24.42 -17 02 00.9 (J2000.0)

This is a 50″ long blue bipolar nebula in the Sagittarius constellation. It was found in DSS plates when hunting for Variable stars. The nebula is also very obvious in the Pan-STARRS g filter, but hardly visible in other optical images, including Halpha.

panstarrs dss Pre 30Discovery DSS2 image, and High resolution Pan-STARRS1 (r + g + i) extract showing Pre 30. Image credit: DSS2 Aladin Lite and the Pan-STARRS1 Science Consortium.

The nebulosity stems from a redder central object that emits strongly in the mid-IR. In WISE the object appears best in the W3 and W4 band, but is also relatively significant in the W1 and W2 bands too. Furthermore, the central object seems to have a *slightly* brighter in the UKST Halpha images in comparison to the Short Red ones.

In July-August, 2017 Johannes Schedler of the CHART32 team captured a beautiful high resolution image of Pre 30. His image is a combination of an OIII and RGB exposures (total 25 hours). Unlike one would expect from a Planetary Nebula, Pre 30 doesn’t appear exceptionally bright in OIII images. This is an indication that it might be a Proto-Planetary Nebula instead of a true PN. It is also possible that Pre 30 could be the result of a symbiotic star system (LDû et al., 2018).

Pre30_c100_labelCombined OIII + RGB image of Pre 30 as seen by CHART32. Image credit: Johannes Schedler/CHART32.

I later discovered that Pre 30 presented a variable light curve, with luminosity varying by V= 0.3 mag regularly with a period of 340 days (according to ASAS-SN data). Such variations are very common in the case of Proto-PNe, hence it has been listed as such a candidate by AAVSO’s VSX:

Pre 30 lightcurveFolded light curve of Pre 30, based on ASAS-SN data. (c) Trygve Prestgard

The CHART32 image also reveals Pre 30 to have a similar appearance to Minkowski’s Butterfly nebula (M 2-9). The nebula probably went undiscovered due to its lack of Halpha signal (hence missed by Halpha surveys, such as MASH).

Pre 6, Pre 31 and Pre 32

These are small (quasi-)stellar Planetary Nebula candidates. Despite their stellar nature, their colours in SDSS and Pan-STARRS1 are those expected from PNe. Furtermore, Pre 6 and Pre 32 have a favorable Mid-IR signal in WISE. Pre 31 doesnt seem to be detectable in any Infrared images. Pre 6 however seems to be an independent discovery, as it has been mentioned in a paper from 2015 (Froebrich et al). Pre 32 seems to be surrounded by a faint halo seen in Pan-STARRS1 and DSS2 images according to Pascal Le Dû (France).

stellar sdss PNe Pre 6 31 32

Planetary Nebula candidates Pre 6 (PN UWISH2 050.78036+1.18512), Pre 31 and Pre 32 seen in SDSS images. Image credit: SDSS Aladn Lite.


Pre 10 and Pre 33

These are two bipolar Planetary Nebula candidates located in the southern hemisphere. Pre 10 was discovered in AllWISE and SHS Halpha images in 2016. The object presents a noticeable bipolar nature in SHS Halpha and DECaPS images. In DSS Red the object is faintly visible, appearing elongated.

Pre 33 was discovered in 2017 in AllWISE and DSS images. In the optical wavelengths, the object essentially appears in the DSS Blue plates (while hardly any traces appear in SHS Halpha images!). While the object might ressemble a galaxy at first glance (LDû et al., 2018), ASAS-SN shows the object to display long-period variations, similarly to Pre 30, a proto-planetary nebula candidate. This would explain the lack of significant Halpha emissions as seen in SHS Halpha. The WISE signal is also similar to red giant stars, rather than PNe, which is also in favour of the latter.

Pre 10 Pre 33DECaPS and DSS Blue image extract of Pre 10 and Pre 33. Notice the bipolar nature of both these objects (especially in the case of Pre 33). Image credit: DECaPS Aladin Lite and SuperCosmos Sky Survey DSS2 Blue.

Pre_33_Phase curvePhase plot pf Pre 33, based on a period of 218 days. The low amplitude LPV-like sinuoisdal variations in brightness are typical of PPNe. Credit: ASAS-SN data.


Pre 25, Pre 26, Pre 34, Pre 36

These are some relatively large circular and elliptical PN candidates. Their PN classification is further supported by their signal in WISE images. However, their color and also their morphology seem to indicate that they might in fact be Cometary Globules rather than true PNe. Candidates Pre 25, 34 and 36 all seem to appear seem to have a grey-brown appearence in SDSS and Pan-STARRS1 imagery. Pre 26 seems to be located in a field with much similar nearby nebulosity of globular nature, with DSS colours not common in Planetary Nebulae.

cometary globule nebulae pnePlanetary Nebulae candidates Pre 25, 26, 34 and 36 as seen in DSS2 and SDSS images. Image credit: DSS2 and SDSS


PrKn 1

This nebula is a co-discovery along with Matthias Kronberger (Austria) of the Deep Sky Hunters (DSH) team. I found in October 2017, in AllWISE images via Aladin Lite. In these images, it appears an obvious and well defined disk, only visible in W4 (much like that of a Planetary Nebula). I first thought the WISE signal was an artefact, but when looking at ARAKI Far-IR images I noticed a faint IR source in those images too. Furthermore, when browsing SIMBAD I found that IRAS had designated the object as an IR source (hence it was observed by IRAS too).

PrKn mid_IRDiscovery AllWISE image of PrKn 1, and my confirmation image of this IR source in AKARI Far-IR images. Image credit: Aladin Lite.

The nebula did not appear in DSS2 and Pan-STARRS1 images, hence I could not yet report the object to Agnès Acker and Pascal Le Dû, as an optical signal of some sort is an essential criteria. Only a small blue star (likely white dwarf) was visible in optical images. I mentioned the object on the DSH forum, in the hope that someone could spread the word to get it images. Luckily, the DSH team was able to take narrow-band Halpha and OIII images of the area in November 2017, in which the nebula definitely appeared, especially in OIII. The nebula is only a degree east of NGC 2402, in the Canis Major constellation.

PreKn 1 OIII LCOOIII exposure of PrKn 1 taken from Las Campanas Observator (LCO). Image credit: LCO George Jacoby.

Pre 37, Pre 38, Pre 39, Pre 40

I found Pre 37 using WISE and SHS in 2016, but the resolution and limiting magnitude of these images were not enough to keep these objects as definite PN candidates. It was only in 2018 with the release of the DECaPS survey data that I was able to confirm my sightnings. Pre 38, Pre 39 and Pre 40 were found by combining WISE and DECaPS data in 2018, when I soon realized the increadible properties of DECaPS! 🙂 These objects are highly reddened by interstellar matter, especially Pre 38. Pre 37 and Pre 39 appears rather disk like, in comparison to Pre 38 which has a more “bean shaped” morphology and Pre 40 which seems rather amorphous (or round?). Pascal Le Dû notes that Pre 38 appears as a small compact nebula in DSS Red. Pre 40 also appears in SHS Halpha images, as a faint stellar object (being otherwise invisible in SHS Short red).

Pre 37 38 39 40Planetary Nebula candidates Pre 37, 38, 39 and 40 as seen in DECaPS data. Notice how Pre 38, Pre 39 and Pre 40 seem very reddened, as they appear to be strongly obscured by the surrounding gas and dust. Image credit: DECaPS Aladin Lite.


PrePa 1

I share this discovery with amateur astronomer Dana Patchick (USA). PrePa 1 is a small, round and compact PN candidate in Crux. It was found when searching the AllWISE images for unknown PNe, in which the object appeared obvious, with the typical Mid-IR signature of a PN! PrePa 1 also appears relatively bright and nebulous in SHS Halpha images! Pascal Le Dû notes the presence of a possible 2′ large halo surrounding the nebula, as seen in DECaPS. When looking closely at this faint surrounding nebulosity, it seems to possibly be elongated in nature.

PrePa 1DECaPS images of PrePa 1. The left image shows the object and the possible faint halo associated with it (marked by white lines), while the right image is a zoom up close on PrePa 1. Image credit: DECaPS Aladin Lite.

PrePa 1 AllwiseImage extract of the discovery AllWISE image of PrePa 1. Notice its “red” appearance in these images, typical of PNe! Image credit: AllWISE Aladin Lite.


Pre 43

I first noticed this possible Planetary Nebula in images from the WISE and DECaPS surveys online, where it appears as a rather heterogeneous, clumpy and elongated blue nebula. In images from the Digitalized Sky Survey (DSS) the nebula mixes rather well with the surrounding nebulosity, but DECaPS, Narrow-band (OIII and Halpha) and WISE Mid-Infrared images clearly indicate it to be seperate and an independent nebula!

Pre 43 BertPre 43 as seen in a OIII+NII image extact taken by Bert Van Donkelaar. The nebula appears as a tiny blue patch of nebulosity at the center of this image. The image indicates that Pre 43 emits strongly in the OIII band, typical of PNe. (c) Bert Van Donkelaar.

Pre 43 decapsDECaPS Image extract showing Pre 43. In these images it appears as a complex, heterogeneous, clumpy and elongated blue nebula. The brightest part of this nebula is 0.5′ x 0.7′ in size. This is surrounded by a faint, vague and blue halo measuring perhaps 2′ x 1′ in size. Image credit: DECaPS Aladin Lite.

shs Pre 43 short red halphaImage comparison between a SHS Short Red and Halpha frame showing Pre 43. Notice how the nebula only seems to appear in Halpha. This is typical of Planetary Nebulae as they most often have hydrogen emissions. Image credit: SuperCosmos Halpha Sky Survey.


Pre 44

In the region nearby Pre 43, I noticed this previously unknown circular blue PN candidate in the Carina constellation. I first found the object in AllWISE images, in which the object appeared as an obvious disk in the W4 band. The object appears very clearly in DECaPS images, but it can also faintly be seen in DSS Blue and SHS Halpha images! An obvious central (white dwarf?) star can also be seen!  The object has an apparent diameter of about 1′. It’s located about 7′ NE of the Vmag = +6 star HD 97451; a little over 30′ NNE of an relatively bright HII region (BRAN 347) and about 1° NEE of the bright open cluster NGC 3532.

DECaPS 2'x2' crop (enhanced & cleaned up)DECaPS image extract showing Pre 44. Notice its obvious blue circular morphology, along with its central blue star! This image was corrected by Dana Patchick (elimination of artefacts). Image credit: Dana Patchick DECaPS Aladin Lite.

SHS Halpha 2'x2' (sized to match)SHS Halpha image of Pre 44 processed by Dana Patchick. In these images the nebula is very faint and annular. Image credit: Dana Patchick and the SuperCosmos Sky Survey.


Pre 46

Coordinates: 17 01 18.25 -36 52 22.0 (J2000.0)

I found this 20″-large quasi-circular PN candidate when scrolling through DECaPS images from the Aladin Lite interface in May, 2018.  In these images the object appears as an obvious blue-green sphere, with the inner regions appearing bluer than the outer edges. At first glance, I was certain the nebula was known. Indeed, it appeared very obvious in SHS Halpha images, typically an object to have been picked up by the MASH team. However, after consulting the various online ressources, with the help of Dana Patchick,  we soon realized that the object was most likely unreported. Consequently, Pascal Le Dû designated the object Pre 46.

Pre 46 DECaPSDiscovery image extract of Pre 46. Notice the obvious round structure of the object, with a nice blue-green (g band – r band ) colour gradient inside – outward. Image credit: DECaPS Aladin Lite.

In SHS Halpha images, the object appears annular, with the Halpha emissions correlating to the redder (green) edges of the nebula (see image below). In SHS Short Red the object is almost undetectable. The optical DSS plates also seem to show the nebula well. A close look at WISE data shows weak spots in the W3 and  W4 bands.

Pre 46 SHSSHS Short red (left) and Halpha (right) image extract showing Pre 46. Notice how its appearance Halpha greatly outshines its r-band appearance. Image credit: SuperCosmos Halpha Sky Survey.

Despite being significantly fainter and apparently smaller, Pre 46 has a rather similar appearance to Planetary Nebula NeVe 3-4 (among other NeVe PNe), located in Puppis (as can be seen in the DECaPS image extract below).

NeVe_3_4Planetary nebula NeVe 3-4 as seen in a coloured DECaPS extract. Notice its somewhat similar appearence to Pre 46. Image credit: DECaPS Aladin Lite.


Pre 47

Coordinates: 15 52 6.6 -51 38 12 (J2000.0)

I found this faint PN candidate in DECaPS images, using Aladin Lite. Unsurprisingly, it’s undetectable in the DSS plates, and only faintly in SHS SHort Red images. It appears significantly brighter in SHS Halpha images however. DECaPS also seems to possibly indicate a central blue star. The nebula is not associated to any detectable WISE signal. Interestingly, the nebula is only 8′ SE of the very bright PN Shapley (Sp) 1! Hence, it has been recovered in some wide-field images taken of Sp 1. These include images from astrophotographers such as Steve Crouch, Don Goldman and Michael Sidonio.

Pre 47Pre 47 as seen in DECaPS (discovery images), SHS Short red and SHS Halpha. Note that the nebula appears relatively bright in SHS Halpha, in comparison to the other optical survey images available for this object. Image credit: Aladin Lite and SuperCosmos Halpha Sky Survey.

Unfortunatly, based on images from the APO team, it appears that Pre 47 does not emit significantly in the OIII band. This might be an indication that this might not be a true Planetary Nebula. Perhaps this could be a Stroemgen sphere? Only a spectra can truly confirm its nature.

OIII Pre 47A 200% crop OIII image extract showing no obvious trace of Pre 47. Image credit: APO team.

Halpha Pre 47 APO teamA 200% crop Halpha image extract clearly showing Pre 47. Image credit: APO team.

Despite being alot fainter and having a much smaller angular diameter, it could be possible that Pre 47 is similar in nature to Fe 7 (see DSS image extract below).

Fe7_nebulaColoured DSS2 image showing Fe 7, an object that might possibly be similar to Pre 47, in my opinion. Image credit: DSS2

Pre 50

Coordinates: 08 07 15.80 -35 26 39.00 (J2000.0)

I discovered this object while searching for nebulae nearby the surrounding of Sankalp Mohan’s Mo 18 discovery, a possible Planetary nebula or cometary globule (see my blog post: ). It didn’t take too long before I noticed a circular W4 signal in AllWISE images. DECaPS  showed the optical counterpart as a blue Bipolar nebula, with an obvious blue central star. SHS images suggests that the nebula emits significantly in the Halpha band. The object was also recovered in a wide-field image taken by the APO team. It could also be possible that Pre 50 is a reflection nebula.

Pre 50Pre 50 as seen in DECaPS, SHS Halpha, and a combined OIII+Halpha image by the APO team. (c) Apo Team. Supercosmos Halpha Sky Survey and DECaPS Aladin Lite.


Pre 51

Coordinates: 11 54 46.04 -59 31 50.5 (J2000.0)

I found this nebula using the AllWISE images from Aladin Lite, where it appeared quite obvious in the W4 band. This Mid-IR source was associated to a blue arc nebula, surrounding a pale blue star (according to DECaPS observations). It is hence quite likely that Pre 51 corresponds to a Planetary Nebula, but only spectroscopic observations can confirm this for sure.

Pre_51_decapsPre 51 as seen in a DECaPS image extract. Notice the blue arc-like nebulosity surrounding an obvious CSPN. Some of the nebulosity is perhaps hidden by some of the nearby stars. Image credit: DECaPS Aladin Lite.

PreMo 1

Coordinates: 09 26 12.00 -49 57 31.0 (J2000.0)

I found this nebula using the AllWISE images from Aladin Lite in early July, while discussing Planetary Nebulae with Gabriel Murawski (Poland). Despite an obvious WISE signal, typical of a PN, the copitcal counterpart corresponds to a very faint nebulosity, best visible in SHS Halpha. In DECaPS it appears somewhat blue. Sankalp Mohan (India) reported this nebula independently to Pascal within weeks of my report. Consequently, it was given dual-credit. DECaPS imagery seem to reveal a possible CSPN, but it could also be a background star.

PreMo_1_DECaPSPreMo 1 as seen in a DECaPS image extract. The nebula appears somewhat round, with perhaps hunts of a CSPN (which could also be a background star?). Image credit: DECaPS Aladin Lite.