17 replies to this topic

[Redbetter]

On 2/26/25 I observed SN 2025bdr with the 20” under dark skies.  At 357x in the moments of better seeing, the Type Ia-91T would become briefly stellar, just resolved off the SW end of the galaxy’s main SW/NE glow.   It was about 16.4 V mag at the time.

 

This observation was not much different than many others I have made since 2016, except that it marked the 500th supernova I have observed in that span.  Although I had observed a few supernovae since ~1996, I had not kept track of them until I became more serious about dark sky observing again in 2016. 

 

Relying on David Bishop’s Bright/Latest Supernova page, I began making regular lists of good candidates for visual observation in 2016.  At first I observed only a few bright and easy ones, then a few dozen per year that were primarily in NGC/IC and other standard catalogs of visually observable galaxies.   For these the galaxies were as much my interest as the dying star.  In 2021 I became more methodical in tracking down what might be in range of my scope, and began pursuing more elusive ones where the galaxy was not visible.   This soon increased to the level of a stretch goal of ~100 SNe per year.  

 

I don't know if I will try to continue at this pace to see if I can eventually reach 750 or 1,000.  However, I have reviewed my logs to provide some information about the sample and to answer some questions folks might ask..

 

SNe count by year.
2016 ---- 3
2017 --- 26
2018 --- 35
2019 --- 27
2020 --- 32
2021 --- 67
2022 --- 82
2023 -- 107
2024 –-- 97
2025 --- 24 so far.  The most I have observed in any single session is 10 on 2/25/25.  The most I have successfully observed in any calendar month is 19 in May of 2023.

 

From what I can tell I have observed all of the types and sub-classes except for kilonovae and the superluminous SLSN-I and SLSN-II.  However, there is an asterisk with the SLSN's as that designation seems to be only on very distant ones that have not been further classified, while I have observed SN 2018cow which has been classed as a Type Ib or Type Ic-BL and referred to as superluminous. Here is my count by types:

Type Ia --------- 312
Type Ia-91T ----- 23
Type Ia-91bg ----- 6
Type Ia-02cx ----- 4
Type Ia-pec ------- 4
Type Ia-SC ------- 3
Type Ib ---------- 10 
Type Ibn ---------  1
Type Ib/c --------- 4
Type Ic -------- --- 6
Type Ic-pec --- --- 2
Type Ic-BL ---- --- 6
Type Icn ---------- 2
Type II ---------- 87
Type II-pec -- ---- 1
Type IIb ---------- 3
Type IIL ---------- 1
Type IIn --------- 16
Type IIP ---------- 8
Type SN ---------- 1   (Classed as SN but not further sub-classified.)

 

I have observed supernovae in 54 constellations.  The top five constellations are:  Ursa Major and Virgo at 44 each, Pegasus at 29, Bootes at 27 and Hercules at 24.  In the least likely category (among those that were not zero) I observed one in Pyxis.

 

From what I can tell, the one farthest south I have observed is SN 2021wjb in IC 4931 in Sagittarius at -38h 34m 38s.  Two others were in the -38h 11m plus range.

 

The most distant I have successfully seen is SN 2025ah, a Type IIn at z=0.0815 at ~1.1 billion light years.  The next most distant is SN 2023usc (also a Type IIn) at z=0.06.   These are two of the 6 that have exceeded z=0.05.  The mean redshift of the 500 has been z=0.020.  The median has been z=0.018.  

 

While I haven't kept track of all the estimated (or measured) magnitudes on the night of my observation, the typical observation is in the 16 mag range.  I generally don't try to observe supernovae that I believe will be near 17.5 mag or dimmer since reaching this deep is very condition dependent.  However, I have succeeded on a few that proved to be in the high 17's.  Most of the time ones this dim are clean misses and ones in the low 17's are challenging with a number unseen.

[Keith Rivich]

That's incredible Red! 

 

Imagine what you could do with go-to and tracking 

[fftulip]

That's amazing.  I was wondering if you have goto or push to with your 20".  In other words, how do you know you're looking at the right place?

Or is a supernova obvious when it's shining in a distant galaxy - what if it might be a foreground star?

[Keith Rivich]

That's amazing.  I was wondering if you have goto or push to with your 20".  In other words, how do you know you're looking at the right place?

Or is a supernova obvious when it's shining in a distant galaxy - what if it might be a foreground star?

[oldphotonm]

Dang Red, that IS amazing.

 

Thanks for the tip about David Bishops list page; a new set of deepsky goodies to plan for!!

[Redbetter]

That's amazing.  I was wondering if you have goto or push to with your 20".  In other words, how do you know you're looking at the right place?

Or is a supernova obvious when it's shining in a distant galaxy - what if it might be a foreground star?

Neither.  All manual with visual finders, and I star/galaxy hop to my targets.  I have to assemble, set up, and collimate each session other than during camping trips.  Not a single one of these involved any electronic finding or tracking.  One/possibly two were with a small refractor used to locate bright SN in different observing positions that my 20" could not easily access due to low positions in a very tall tree line.  I observed some others with small refractors, just because I could, but these latter were after observation with the 20".

 

With DSC's 20+ years ago I quickly realized that the pointing accuracy was poor enough with the scope that I would never know if I was in the right place for dimmer targets (unless i happened to see them in the FOV as well.)  I did some multi-star calibration checks, and then did hops to visually identifiable objects, yet the warp corrections were much too large for the DSC's to be useful.  I did several things recommended to cure this, with zero success.  So I never quit finding things manually.

 

I use Uranometria as my primary charts, and usually can find nearly any galaxy plotted there...but not always, and sometimes I see several other galaxies that are not plotted, which is very confusing.  Generally, if a galaxy is in Uranometria, a simple sketch of the expected position relative to the galaxy and field stars (listing mags) will work as a finder chart.  However, the majority of my SNe targets are in galaxies that are dim enough to be challenging, not visible at all, not plotted in Uranometria, or are in a field with enough other galaxies and stars that I need a detailed finder chart for ID.  

 

So I make finder charts using Wikisky, using screen captures, then cropping, printing B&W inverted color images of the field, with the closest Uranometria field objects marked and noted--as well as the position penciled in on the atlas page for the star hop.  I list mags of stars down into the 17's.   And when I am done finding the SN I attempt to locate and observe whatever other galaxies are in the same field or on my printed finder images.  This is often one or two, sometimes three to five, and rarely between half a dozen and a dozen. 

 

Other than a few bright ones in NGC/IC galaxies or easily found dimmer galaxies, SNe would be tough to identify without accounting for field stars (and companion galaxy cores...which are not uncommon with a 20" and sometimes not cataloged as such.)  Therefore making some sort of finder image/sketch is very helpful and reduces confusion about what is seen.  However, it can be challenging to appreciate the scale, so field pattern recognition with recorded magnitudes helps greatly.  It is not uncommon for me to think I am not seeing something, then realize I am not interpreting the pattern and offsets correctly.   When I get it sorted I realize that something I thought was a superposed field star is actually the SN hiding in plain sight, and the pattern suddenly makes sense.

 

Some of the tougher SNe to be sufficiently certain of are ones that are in close proximity to a galaxy core (a few arcseconds).  The brighter the galaxy/core the tougher the SN is to distinguish when near center.  In some cases one is merely looking for an unusually bright core.  Since I have looked at thousands of other galaxies of similar magnitude, I can often see tell-tale differences of overbrightening due to a SN superposed on the core.  With others near the night's TLM (telescopic limiting magnitude) the key identifying difference is a marginally resolved semi-stellar second core (dual core) near the galaxy core/center.  These can be quite ephemeral/uncertain, but the consistent position (angle) is often the critical piece of supporting evidence for a real observation vs. spurious.

[Redbetter]

Dang Red, that IS amazing.

 

Thanks for the tip about David Bishops list page; a new set of deepsky goodies to plan for!!

I link to his page in my monthly threads.  I have learned to better use his pages over the years. I have also gotten better at using the ZTF explorer (which has frequent interface problems) to hunt for rising candidates that have not yet made Bishop's page.  So I come up with a few that don't make his page in time.  TNS's classification reports and photometry listings often include the ZTF designation which can be hacked in to locate ZTF light curves for one's that are missing.  ZTF was up and running some time in 2018, and that facilitated improved timely recognition of SNe, making possible the large hauls I have made in recent years.

 

I don't know what will happen when the Vera C. Rubin scope is up and running in normal mode.  It could completely bury Bishop's site with data for very dim SNe, although with a heavily southern hemisphere bias.  A lot will depend on the SN spectra pipeline.

[City Kid]

Of those 500 SN you've observed have there been any two in the same galaxy?

[Keith Rivich]

That's amazing.  I was wondering if you have goto or push to with your 20".  In other words, how do you know you're looking at the right place?

Or is a supernova obvious when it's shining in a distant galaxy - what if it might be a foreground star?

With experience, a good set of charts matched to your scope and skies plus a well aligned finder you can find any point in the sky with confidence. Doesn't even have to be an object there, just need enough stars to match up with the chart. 

 

I do use go-to with very good success. The system is accurate enough to put my target in the FOV of my 35 Panoptic, most times even my 13mm. From there I "visually plate solve" the field to match the chart then adjust as needed. 

 

To stay on topic matching stars near galaxies can be interesting as most charts don't show stars that are in close to the galaxy. Megastar does Ok but it does miss quite a few leading to many a supernovae discoveries only to be dashed when looking at a picture!

Edited by Keith Rivich, 19 March 2025 - 03:51 PM.

[Redbetter]

Of those 500 SN you've observed have there been any two in the same galaxy?

Yes, but not visible at the same time.  There have been a time or two when more than one supernova was present in a galaxy, but one was below the visual threshold.  I can't recall the specifics at this time.

 

There are at least four galaxies in which I have observed two SNe:

• NGC 3147 (SN 2021do, SN 2021hpr)
• NGC 3367 (SN 2018kp, SN 2022ewj)
• NGC 3938 (SN 2017ein, SN 2022xlp)
• NGC 7769 (SN 2019iex, SN 2022mxv)

Oddly enough I have not managed to catch two in the two most prolific galaxies, NGC 6946 and NGC 3690.  NGC 3690 has had a lot in recent years, but most have been too dim visually (including SN 2024gzk for which there was some erroneously bright photometry--no sign of it visually when I tried.)

[j.gardavsky]

Hello Red,

 

the 500 SN visually, is a great achievement, congrartulations!

 

Considering ther increasing number of your supernovas counts year-to-year, you will certainly reach above 1,000 in the next years.

 

Clear skies, and many great observing sessions to you,

JG

[Epick Crom]

Hi Red,

 

Observing 500 supernova is mammoth effort,congratulations! I have only observed one supernova so far 

 

Keep up the good work and wishing you clear skies. 

[balcon3]

A very impressive achievement ! I was wondering, do you have a favorite or favorites?

[CowTipton]

A very impressive achievement ! I was wondering, do you have a favorite or favorites?

This is my question also.  Which have been most memorable?

 

For the record I've seen one.  2022hrs near Messier 60.

Edited by CowTipton, 21 March 2025 - 03:35 PM.

[Redbetter]

A very impressive achievement ! I was wondering, do you have a favorite or favorites?

 

This is my question also.  Which have been most memorable?

 

For the record I've seen one.  2022hrs near Messier 60.

 

There are just too many to list.  Each one has its own story.  Some were the first time I managed to catch a more difficult sub type like the Type Ia-91bg or Type Ia-02cx.

 

Since I am scouring through the supernova page and ZTF reports for several weeks each month looking for new targets, there is always something new.  So what was very interesting last month is quickly shuffled to long term memory.  I am reminded of these more when some question arises about a type or I am looking for examples of something I have observed before.  Shuffling through log lists then notes/images refreshes my memory.  Sometimes the designation sticks in my head because it is amusing/memorable (such as SN 2018cow which was unusually bright in absolute magnitude.)

 

SN 2017eaw in NGC 6946 was memorable for being visible in small apertures and well placed to show people.  It was the first one I viewed with the 110ED.  SN 2020ue in NGC 4636 was easily visible at 60x in the AT60ED.  SN 2023ixf in M101 put on a bright and long show, so that one was pretty special.  SN 2025ah at ~1.1 billion light years was memorable for being visually detected at all since it is an outlier in terms of reported redshift.

 

There have been a number that presented as "double core" and were very difficult to resolve.  Just seeing them at all made them memorable, because they required effort.  Some have been notable because they were not quite where I thought they should be and I was coming up blank in the expected location, but seeing something elsewhere--when I checked online images later the position I observed them at was indeed correct. Some of the completely "not seen" ones have been memorable in proving that I am not letting confirmation bias yield false positives.  And in a case or two, they weren't seen because the reported magnitude was off by 1 or even 2 magnitude.

[kfiscus]

500 is stunning.  I'm @ 3...

[ABQJeff]

Wow! Just Wow!! Congratulations on 500 SN! You are an inspiration to what can be done with a big scope in dark skies (gives me ideas!)

Keep it up, I look forward to seeing your 750 and 1000 SN marks.

[StanH]

Congratulations on 500!  That is a remarkable achievement.  My personal goal set years ago was 200, but that appears now out of reach.  My total is 170 though there are a handful of objects for which there is some debate whether they were supernovae or not.