Bill S

Peter, I was using an f/5 200 mm Newtonian with a 0.5x focal reducer making the scope about f/3.5. Lodestar X2 camera. All mounted on an HEQ5 Pro. Software was Starlight Live for capture and Jocular for live stacking and stretching etc. The snapshot I showed is 3 x 15 S. Sky brightness SQM was was 19.90 so Bortle 5.

I've had no chance to observe comet 12P but I have been looking for a few others. Last night I looked at 2023 A3 . Here's a snapshot. At least there is a hint of a tail. Mag 11. Still 3 AU from Sun. Possible bright comet in the future. Around October 2024. Mag 0 or better. I'll believe it when it happens. Watch this space...

I looked at a couple more supernovae on 12/13 April. 2024efn Discovered 12 March Currently mag 15.9. Another type IA. ~300 Mly The other one was 2024cld. Discovered 13 March MG 16.0. Type II ~132 Mly

A clear night gave me the chance to have a look at some supernovae. I also caught up on December 2023 to March's Webb Deep Sky Society's Galaxies of the Month/ (I may post these separately.) I used the Rochester supernova site to find details and compare my snapshots with others' images. First up was 2024ehs. Discovered 15 March. Currently mag 14.3 Type II (i.e. a core collapse of a large star at the end of its life) The second one I looked at was 2024bch. Discovered 29 January. Currently mag 14.6 Type Iin. This one is also a core collapse supernova. However it's a rarer type. Type IIn have narrow hydrogen emission lines in their spectra (hence the 'n'). The special properties of this type are thought to be due to interaction of the expanding supernova with material around the star, the circumstellar medium. I then looked at 2024exw. Discovered 4 March Currently mag 15.0 Type II. The large bright galaxy to the top left of the snapshot is M98. Finally I looked at 2024gy. Discovered 4 January. Currently mag 14.8 Type IA. (i.e this is the type of supernova where the two stars are involved and material accretes on a white dwarf until it reaches a limiting point (Chandrasekhar limit, about 1.4 the Sun's mass) and explodes. They are useful standard candles for working out the distance of the host galaxy. Peter C65 recently posted a set of images of this galaxy and supernova showing them over several months. 200mm F/5 Newtonian with focal reducer making it about F/3.5. Lodestar X2 with Starlight Live and Jocular. Just need a few more clear nights!

I like to have a bit of look for some of the supernovae listed on the Rochester site (https://rochesterastronomy.org/snimages/). One that I looked at during March is SN 2023bee in NGC 2708 (Hydra). This was discovered at the beginning of February and is said to have reached a maximum brightness of about 13. It was a Type Ia. I also looked for it a few days ago and it was still visible but noticeably dimmer. I uploaded images from the March and April viewings to astrometry.net and plate solved them. I then loaded them into ASTAP to see if I could get reasonable magnitudes. The March one came out as 14.0. A result published around the same date on the Rochester site was 14.2 and marked V, so presumably a photometric V filter was used. The April figure for me was 15.7, The closest date's Rochester result was 15.4 G (presumably a green filter). The supernova looks a long way out from the main part of the galaxy.

And some more Arps (new to me) from a couple of recent sessions. Two nights observing in a row - amazing. Arp 83 NGC 3799 and 3800. Bright arm probably due to tidal interaction. The disturbance may lead to more star formation. Arp 263 Irregular galaxy. NGC 3239. Arp class Irregular clumps. Described as a bit of a train wreck. See also http://articles.adsabs.harvard.edu/full/1990PASP..102...41K Arp 94 Arp 94 the large component, NGC 3227, is an unbarred spiral. NGC is a 3226 smaller dwarf elliptical galaxy. NGC 3227 is a Seyfert with an active galactic nucleus. Arp 232 is NGC 2911 and was classified by Arp as being neither spiral nor elliptical. Arp 307 is NGC 2872, NGC 2873 and NGC 2874. The two larger ones were discovered by William Herschel but it took the 72-inch Birr telescope to see NGC 2873 for the first time. Arp 335 – NGC 3509 was classed by Arp as Miscellaneous! It has been described as a possible double (i.e. merging) galaxy but this is debated. A fascinating shape. Arp 43, which is IC 607, is a face on spiral galaxy. It’s rather small in my image but there certainly seems to be quite a lot of detail and it has a bright core. An enjoyable couple of nights.

Arp 242. Ah yes Martin, I thought it looked familiar. Here's a shot from exactly 3 years ago. A bit longer exposure and I've inverted it to show the faint tail of NGC 4676B. Did a bit more Arp spotting last night and the night before. I must sort through them.

A bit of an Arpathon. Just a few hours of observing - picking up some objects that I have not looked at before or have not realised they were Arp galaxies. Arp 89 NGC 2648. PGC 24469 is visible just to the side. Some interaction going on. NGC 2375 interacting with 2735A. About 175 million light years away. I like the long swirly arms on Arp 243. This is NGC 2623. Wikipedia tells us NGC 2623 is the result of two spiral galaxies that have merged. Scientists believe that this situation is similar to what will occur to the Milky Way, which contains the Solar System, and the neighbouring galaxy, the Andromeda Galaxy in four billion years. Something to look forward to! Arp 247 is a galxy cluster IC 2338, UGC 04383 and IC 2339. Arp 215 is NGC 2782. It is a Seyfert 2 galaxy. In other words an active galaxy - the 2 designation refers to spectral characteristics. They have a supermassive black hole with an active accretion disc. Arp 315 is three galaxies – NGC 2830, 2831 and 2832 – from right to left. These, along with 80 more are part of Abell 779. Located about 300 million light years away. Arp 283 is NGC 2798 and 2799 and they look to be interacting. About 85 million light years away. Arp 202 is NGC 2719 and 2719A. NGC 3395 was the Webb Deep Sky Soc Galaxy of the Month for March 2023. Also known as Arp 270 and VV 246. The interesting article on the Webb DSS site (https://webbdeepsky.com/galaxies/2023/) explains that it is thought that the galaxies are in the early stages of interaction. OK, that's quite enough for now!

That’s interesting. I’ll definitely want to read up about that and see if I can see any of the details you’ve managed to capture.

Thank you for sorting that out for us, Robin.

Re. The offset figures. Martin Meredith's suggestion that the offset refers to a nearby bright star is reasonable because, as he says, the front page of the Rochester supernovae website talks about that. There is another possibility. Some details of supernovae refer to an offset from the centre of the host galaxy. For example The ASAS-SN Bright Supernova Catalog – IV. 2017 ... '...we report these coordinates in Table 1. The offsets between the SNe and the centers of their host galaxies are also reported in the Table...' https://arxiv.org/pdf/1811.08904.pdf In this paper the offsets are in arcseconds. It's of interest what the offset refers to but not of importance for using the website so far as I can see. Thank you for your interest and comments. Happy supernova spotting! Regards Bill

Incidentally I still find it amazing that I could see the NGC 5894 and its supernova so easily. I posted an 8 minute snapshot to show things clearly but things were perfectly obvious in a 15 second sub.

Hello Pete Yes, indeed. The Rochester one is where I normally look. Cheers Bill

One from a few days ago 29 September. The host galaxy is NGC 5894, an edge on spiral galaxy about 130 million light years away. The galaxy is listed as SBm. The supernova was discovered on 22 July this year and is a Type II i.e. a core-collapse. I was pleased to see it is was still clearly visible. The same night I also looked at NGC 6745 to see if I could see SN 2022prr. This was discovered on 27 July. With a bit of wishful thinking I believe I can see it. The galaxy is an irregular galaxy about 206 million light years away. The supernova has been classified as a Type IIn. The n refers to particularly narrow spectral lines possibly linked to interaction of the ejected material with gas around the star. Bill

Ooh yes, Martin. I see what you mean. I had another look at this early this morning and here's a snapshot labelled up with the ones you drew attention to. As you say, various other objects around too.