77 replies to this topic

[mwr]

"The spectrum shows a series of high equivalent width flash ionization lines of H, He, C, and N, typical of Type II SNe in the flash ionization phase (e.g. Yaron et al. 2017). The redshift is the catalogued redshift of the the host galaxy (M101)." 

 

https://www.wis-tns....sification-cert

 

https://britastro.or...pernova-in-m101

[jetty]

Despite forest fire smoke and aurora so bad that I can't even see Vega visually, I managed to image this tonight and blink it against an M101 image I took 3 days ago.

 

Redcat 71, with a custom built camera / system for the Raspberry Pi I'm testing.  First camera (16th) is different to the one today. (first is more for occultations, 2nd is for regular astro).

Tonight I just got lucky in that fine smoke particles are more transparent to infrared, and the camera is astro modified (OSC).

 

https://twitter.com/...3170705410?s=20

[robin_astro]

ZTF report a 10 hours pre-discovery detection at mag 15.9 (g) 2023-05-19 07:45:07 and a negative (fainter than 21.3) 2023-5-16 19:35:38.00
https://www.wis-tns....ronote/2023-120

so any deep images taken between those dates could be of interest

 

I tried  to get a spectrum last night but the clear skies stubbornly remained just a few miles east of my location

 

 

Cheers

Robin

[idclimber]

The supernova shows up on my first sub taken Thursday night shortly after midnight. This would be May 19 at 0604hrs UTC ( I am US mountain time which I believe is -6)

[robin_astro]

The supernova shows up on my first sub taken Thursday night shortly after midnight. This would be May 19 at 0604hrs UTC ( I am US mountain time which I believe is -6)

There is a report of another pre-discovery image taken within a few minutes of yours 

https://www.wis-tns....ronote/2023-123

 

I bet there are others even earlier. Keep them coming !

Edited by robin_astro, 20 May 2023 - 12:12 PM.

[idclimber]

There is a report of another pre-discovery image taken within a few minutes of yours 

https://www.wis-tns....ronote/2023-123

 

I bet there are others even earlier. Keep them coming !

The 0604 image was the first of my lum set. This was 200+ subs I stared around midnight. Earlier at 10:30pm I started a sequence of Ha and the first sub shows it quite clearly. This is 0426 UTC time according to my fits header. 

 

 

[robin_astro]

I started a sequence of Ha and the first sub shows it quite clearly. This is 0426 UTC time according to my fits header. 

 

That's really cool. The spectrum shows strong H alpha emission so would show up well. I have an account at TNS. If you are interested I could post your observation there on your behalf. DM me if interested

 

Cheers

Robin

[idclimber]

That's really cool. The spectrum shows strong H alpha emission so would show up well. I have an account at TNS. If you are interested I could post your observation there on your behalf. DM me if interested

 

Cheers

Robin

I am happy to have this data made available. I will PM you. 

[robin_astro]

On TNS currently   

 

latest non detection  2023-05-18 10:17:15 (UTC)  (ATLAS)

earliest detection      2023-05-19 03:41:35 (UTC)  (Stephen Limeburner)

 

The gap is closing !

[jonnybravo0311]

I was testing a new scope/camera on the 18th... was pointed at M101. Took just under 30 minutes of luminance data. Here it is stacked:

 

 

Timeline was 2023-05-18 23:06:31 EDT (2023-05-19 03:06:31 UTC) to 2023-05-18 23:39:43 EDT (2023-05-19 03:39:43 UTC). Looking at the first sub, it appears to be there (inverted and annotated):

 

[jetty]

Matches my plate exactly, be sure to tell TNS.

You might also want to look into superstacking or the raws (if they show the supernova) to see if it started during your 30 mins too.  Might have caught it "going" nova.

[jetty]

I have a script I wrote to superstack fits files, if you want to upload the calibrated/registered subs somewhere.

[jonnybravo0311]

Do you want them in FITS or does the native PI XISF format work for you?

[jetty]

fits is best as the script runs on fits, but I have PI too and will convert them if they're not fits.  I've messaged you my email, use wetransfer.com  to that.

Edited by jetty, 20 May 2023 - 07:29 PM.

[jonnybravo0311]

No problem.

 

If anyone wants the data, I've uploaded the registered XISF files to my Google Drive. You can find them here.

 

Note, this data was meant as a test for a new scope/camera. Thankfully M101 is in the center of the frame, so the majority of the issues (tilt/spacing/etc) have no impact. Also, the scale is 1.88"/px, so it's not exactly high resolution.

[jetty]

on it

[jetty]

Seems like you got it early on before it was very bright, but it didn't catch the start.

[jonnybravo0311]

I didn't think I'd caught it happening since I was pretty sure I saw it in every one of the subs when blinking through them. Though we do now know that it happened prior to 2023-05-19 03:06:31 UTC.

[mwr]

Nick James from BAA reports a brightness of 12.0 mag for SN 2023ixf: https://britastro.or...101#post-617427

 

"Spitzer constraints on pre-explosion variability of the SN 2023ixf progenitor": https://www.astronom...org/?read=16042

[mwr]

The similarity of the spectrum recorded by the SPRAT (SPectrograph for the Rapid Acquisition of Transients) of the Liverpool Telescope (https://telescope.li...nst/Inst/SPRAT/) to an early spectrum of SN 1998S is really striking:

 

 

The deconvolution of the H alpha and H beta emission lines of SN 2023ixf fits well the observed line profiles:

 

 

Taking into account the resolution of approximately R=350 (18Å) of the SPRAT (instrumental line broadening) one can calculate a velocity value of approx. 2850 km/s for the broad line profile and a velocity of <640 km/s for the unresolved narrow line profile. The deconvoluted profiles are well comparable the profile of the H alpha line of SN 1998 S (top left profile):

 

 

The publication on SN 1998S could be used as a road map for what to expect from SN 2023ixf in the future:

https://watermark.si...XITcoIIWpeLkr_k

 

 

 

[robin_astro]

Here is the best fit to the SPRAT spectrum as identified by SNID.  SN 1998S type IIn  13 days pre maximum brightness

 

 

The time of the explosion has now been pushed back to earlier than 2023-05-18 21:19:13 UTC thanks to images by Norman Hamann  

https://www.wis-tns....ronote/2023-127

[robin_astro]

A low resolution spectrum with the ALPY600 tonight in poor conditions (high cloud)

https://britastro.or...hp?obs_id=13774

 

and how it looked in the spectrograph guider. 10x15sec  The conditions were so poor the galaxy was tough to see so it was just as well the supernova is so bright (bright enough to guide on directly on the slit)

 

 

Here it is overlaid on the best match from SNID (Type IIn SN 1998S)

 

 

 

Cheers

Robin

[robin_astro]

 

 

The publication on SN 1998S could be used as a road map for what to expect from SN 2023ixf in the future:

https://watermark.si...m/325-3-907.pdf

The direct link to the paper has timed out. do you have the reference ?

 

Thanks

Robin

[mwr]

do you have the reference ?

 

Optical and infrared spectroscopy of the type IIn SN 1998S: days 3–127

Monthly Notices of the Royal Astronomical Society, Volume 325, Issue 3, 2001

https://doi.org/10.1...11.2001.04282.x

 

The DOI link should work permanently.

 

Regards

Matthias

[yuzameh]

robin_a In my searches I've noticed this review paper from a couple of years ago for type IIn.

 

https://arxiv.org/pdf/2107.02179

 

It's not so much the reading of it that's needed (which is worthwhile in itself), it's the fact that in defniing the true SN IIn from other purported SN IIn the papers includes a lorra, lorra IIn spectral plots, including for some as evolving time series.  And it's primarily a spectroscopic assesssment/review.

 

I think I saw this SN being classed as SN IIb on S&T (well, n is next to b on the keyboard).  This is very strange given that apparently a lack of hydrogen lines to speak of, especially Halpha, is a major diagnostic of IIb.  Unless I misread it.

 

Can't find a good lightcurve, but I think it will slow down in brightness now, maybe spend a couple of days crawling up a notch or two, rate of change itself declining, peaking around a fortnight into the outburst and then after three weeks start a crawling fade, with possible blips if more circumstellar shells are hit.  However, I haven't found a long term lightcurve for one so am not sure of the decline profile, nor its typical rate.  As the things are apparently not caused by a sole type of progenitor their decay lightcurves likely aren't homogenous anyway, likely dependent on density, morphology and relative orientation of the latter of the circumstellar material.

 

The latter could lead to a chance of light echoes appearing in time, as does the object's position near a HII region, so that would be a nice distance scale adjunct to the ladder, as I believe those can give quite precise distances.

 

I hope this fortnight level off idea is accurate, I won't have a chance to look at it before the weekend, when the Moon may just start to be a big enough interference for me, given no true night nowadays anyway and light pollution.

Edited by yuzameh, 22 May 2023 - 12:13 PM.