A gravitationally lensed supernova SN 2022qmx at z=0.35

[robin_astro]

An interesting potential opportunity to see a supernova at 0.35 redshift, further than would normally be possible with typical amateur imaging. Currently at r mag 18.8, it is approximately 3 magnitudes brighter than would normally be expected due to gravitational lensing.
https://www.wis-tns.org/astronotes/astronote/2022-180

Hurry though it is already fading !
https://alerce.online/object/ZTF22aaylnhq

 

Cheers
Robin

Edited August 25, 2022 by robin_astro
fixed links

[Xilman]

Twilight is icumen in, so I am going to go looking for it in about an hour's time.

Have you tipped off TA and/or BSS-VSS alert services yet? Should I do so?

 

[Xilman]

12 minutes ago, Xilman said:

Twilight is icumen in, so I am going to go looking for it in about an hour's time.

Have you tipped off TA and/or BSS-VSS alert services yet? Should I do so?

 

I jumped the gun.  Whether Guy issues an E-circular is his call but the BAA-VSS now know about it.

Thanks. Due acks given to you, of course.  Now to open up the observatory.

[Xilman]

Yup, definitely still there on a stack of 16 60s subs. Going to be a bit difficult to measure because g=18.7 EDR3 4389518561481624192 is only a few arc seconds away.  The SN is (eyeball estimate) 19.0 unfiltered, which with my camera matches well to Gaia's g-band photometry.

I'll give it an hour and hope to get SNR in the range 10 - 100 which will be good enough.

 

[Xilman]

Here is my image. 4220 seconds in 71 subs.  0.4m Dilworth, unfiltered SX694.

 

Edited August 26, 2022 by Xilman
Fix typ

[Xilman]

Some crude photometry has now been done.  For comparisons 100 stars within 2 arcminutes of 2022qmx were searched in Gaia EDR3; their positions, G magnitudes and errors therein were saved. These and 2022qmx were analyzed with APT 2.8.2

The magnitude at JD 2459817.361, aka 2022-08-25 20:40 UT, is reported as 20.02 (0.02).

Crude, because my images were unfiltered but have been shown to be a decent match to Gaia G by and large.

[Paul M]

On 26/08/2022 at 15:05, Xilman said:

Here is my image. 4220 seconds in 71 subs.  0.4m Dilworth, unfiltered SX694.

 

I'd like to have had a try for this object. No science, just some pixels in the right spot would be pleasing. But my 0.25m Newt looking through the sky glow of Blackpool Illumintaions is gonna be stretched at mag 20+.

There is a window of oportunity for me tonight but I won't be holding my breath...

[Xilman]

2 hours ago, Paul M said:

I'd like to have had a try for this object. No science, just some pixels in the right spot would be pleasing. But my 0.25m Newt looking through the sky glow of Blackpool Illumintaions is gonna be stretched at mag 20+.

There is a window of oportunity for me tonight but I won't be holding my breath...

Mine took 71 minutes to give a very clear and, indeed, measurable image with a SNR of 50 or so. For detection a SNR of 5 is easily adequate and as SNR goes as sqrt(exposure time) this would suggest exposures 100  times shorter would be sufficient.  Indeed, it is visible in a single 60s sub, as this shows:

Now, I have (0.4/0.25)^2 times the collecting area of you, which is 2.56 times.  All other things being equal (they won't be) you should need 2.56*60 seconds to get the same result. This comes to 2.5 minutes. Stacking 25-50 subs, for a total exposure of 1-2 hours ought to be enough to give you a very clear detection.

Go for it and good luck!

Edited August 27, 2022 by Xilman
Reposition image

[Xilman]

2 hours ago, Paul M said:

I'd like to have had a try for this object. No science, just some pixels in the right spot would be pleasing. But my 0.25m Newt looking through the sky glow of Blackpool Illumintaions is gonna be stretched at mag 20+.

If you get a result and you are unwilling and/or unable to measure it yourself, would you send it to me (even better, make the raw subs available) for me to analyze?  As long as the SNR is at least 15, say, a scientifically useful measurement should be possible.

I would recommend unfiltered (as I used) so as not to throw away any photons from such a faint object. Imaging in the red or near-IR will reduce sky-glow markedly (thereby significantly reducing noise) and the object is intrisically red but will likely reduce the signal by an order of magnitude or so.  What you are looking for is primarily signal with an adequate SNR.

If you are set up to examine subs as they come in, and if you have a R, I, r' or i' filter, you may wish to see how well the trade-off works.

(Actually, imaging from urban sites is best done in the near IR but that is another topic for another thread. UCL students (essentially amateurs at that stage in their career) have made important discoveries from their site in central London.)

Paul

[Paul M]

My sky here is not the best tonight and I might lose it to cirrus yet.

I'm going to set up shortly and planning to use my ASI178 camera which is a better image scale for this job than my ASI071MC Pro. 

I did think about using my 127 mak for the longer f/l but perhaps I'm better going for light gathering over f/l?

I'm more than happy to share any results I get. Indeed, try to stop me!😇

[Xilman]

27 minutes ago, Paul M said:

My sky here is not the best tonight and I might lose it to cirrus yet.

I'm going to set up shortly and planning to use my ASI178 camera which is a better image scale for this job than my ASI071MC Pro. 

I did think about using my 127 mak for the longer f/l but perhaps I'm better going for light gathering over f/l?

I'm more than happy to share any results I get. Indeed, try to stop me!😇

You are photon limited.  Aperture is king here. If you are worried about image scale don't use binning.

[Xilman]

Thick cloud here, so no chance for me tonight.

[Paul M]

All set up. ASI178 on the 250 Newt.

Going out to polar align and focus very soon. 

My next update willbe a sample sub... hopefully. I can live stack in ASTAP too. 

[Paul M]

4 x 240 subs from ASTAP livestack.

Bang on target. no sign of it yet

 

[Xilman]

I'm not so sure ....

To my eye there are two blobs just visible against the noise background. I would guess the SNR at about 3. The uppermost marked object is in exactly the right place for the SN.

Some smart noise reduction and contrast enhancement may well make it clearer. Splitting the RGB panes and stacking them should multiply the SNR by a factor of perhaps 1.4, for instance.

Looking good ...

[robin_astro]

Here it is tonight

40x 20sec  C11+reducer ATIK428

Cool to think this is a single star (an exploding white dwarf) at ~4 billion light years (comoving distance)

Cheers

Robin

Edited August 27, 2022 by robin_astro
added distance

[Paul M]

Struggling to post from my imaging PC via VNC...

About  25  x 240min subs. Dreadful sky. Laser beams scanning the sky  and milky too.

But it's there. I'll get some dark frames now. 

Edited August 27, 2022 by Paul M

[Paul M]

So in the cold light of day I've processed this as best I can. 22 x 240sec stacked and stretched.

I should be happy at detecting a mag 20+ object in that sky. When I looked at the sky Jupiter had a halo. Quite heavy Cirrus affecting the area. Then there was Blackppol Iluminations. This year, for the first time in many years they have a scanning/rotating laser sweeping the sky. It was running until 1am

Anyway, excuses, escuses..

 

[Xilman]

29 minutes ago, Paul M said:

So in the cold light of day I've processed this as best I can. 22 x 240sec stacked and stretched.

I should be happy at detecting a mag 20+ object in that sky. When I looked at the sky Jupiter had a halo. Quite heavy Cirrus affecting the area. Then there was Blackppol Iluminations. This year, for the first time in many years they have a scanning/rotating laser sweeping the sky. It was running until 1am

Anyway, excuses, escuses..

 

Nice work from a particularly bad site and sky. Well done!

 

Any chance of getting hold of your subs? I would like to see what I can do with them. PM me if you wish.  Paul

[Paul M]

1 hour ago, Xilman said:

Any chance of getting hold of your subs? I would like to see what I can do with them. PM me if you wish.  Paul

Absolutely!

I'd love someone to drag something out if that data.

I'm currently indisposed in a small rural hostelry in Cumbria. But I'll maybe put them in a Google drive and send a link later.

[Paul M]

As requested, here (hopefully) is a link to the Subs, I've included the darks too, just in case they help:

https://1drv.ms/u/s!AjKreTWT1vxF2i-CfCA1n7O8vfxm?e=SZM26w

[Xilman]

1 hour ago, Paul M said:

As requested, here (hopefully) is a link to the Subs, I've included the darks too, just in case they help:

https://1drv.ms/u/s!AjKreTWT1vxF2i-CfCA1n7O8vfxm?e=SZM26w

Coming over now. 470MB so far.

It will likely take several hours to make a decent job of the processing and I have other commitments so it may be a week or more before the final results are available.

 

Now gottem.

Edited August 29, 2022 by Xilman
Final sentence

[Paul M]

11 minutes ago, Xilman said:

It will likely take several hours to make a decent job of the processing

It took me several hours to make a bad job of it!

Good luck, I hope my data is worth the effort for you.

[robin_astro]

It has now been imaged by HST and resolved into four lensed components

from
https://www.wis-tns.org/astronotes/astronote/2022-196

Cheers
Robin

[Paul M]

Oh wow! That's incredible. 

I know it was known to be gravitationaly lensed but I never expected that.

For a for a more distant point source to outshine the inntervening galaxy so brightly is just incredible!