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Interestingly there was another transient AT2020ftc discovered the same date 10 hours earlier at almost (but not quite) the same coordinates I wonder if it is the same object, one with incorrect coordinates or perhaps an asteroid?
Forget it. I have just noticed although it has just been put on TNS the discovery date is 2020-04-02. A bit late for them to be announcing it !
https://www.bbc.co.uk/iplayer/episode/m000nysp
at 22min 43sec
Advisory – not suitable for astronomers of a nervous disposition or those with high blood pressure
Another spectrum on a better night (2hr 20min exposure at mag ~15.5 The limit at this resolution). Not much happening compared with a week ago
https://britastro.org/specdb/data_graph.php?obs_id=8021%2C8002&multi=yes
Robin
Interesting. The spectrum seems consistent with a dwarf nova outburst. I managed to salvage a couple of short exposure spectra from aborted runs on the 10th and 12th. They are very noisy though so the only significant feature is the hot continuum shape.
Robin
A short clear spell tonight. Not long enough to get a spectrum but off the spectrograph guider it looked about a magnitude fainter than on 8th
Sorry Andrew, I missed this
Impressive. I have just updated my copy of Visual Spec and I see Valerie has added a wavelets feature
“It’s amazing how people go on finding creative ways to waste their time and resources”
I have to say I’ve done my fair share of that in astronomy too 🙂
I like that the residuals follow the expected shape, noisy at the ends of the spectrum where the sensitivity is lower. It gives confidence that you are removing noise, not signal
Now classified as a type Ia supernova by Italian amateur Claudio Balcon using a home built spectrograph designed around the Star Analyser. Congratulations to Claudio and the XOSS team for their discovery !
Robin
An interesting example has just popped up showing the problems a rogue warm pixel can cause
Looks like it is flickering for a few minutes when it drops. Drifting over a hot/cold pixel perhaps ?
Robin
I don’t have any experience with CMOS (yet) but with my CCD cameras I redo them every few months. Bias frames take no time at all but getting enough long exposure darks eg 1200 sec can take all night so I just leave the camera running on a cloudy night. I then produce a defect map from these and scale the master darks depending on exposure. I find the only significant changes have been with hot and warm pixels (and with one camera a faint line defect appeared) These are not a disaster as a cosmics removal tool normally zaps them but it is better if they can be fixed at source using an up to date defect map
With spectroscopic flats it is important to redo them if you move the wavelength range. I normally do them for each observation with the LHIRES and once a night with the ALPY. it takes little time with the built in calibration units though the results with the LHIRES at the blue end are very suspect due to light leaking past the slit.
I aim to sum at least 20 exposures (30 for ALPY flats where the light level is very low at the blue end)
Cheers
Robin
Estimates from Stan Howerton last night give SN 2020rcq 12.5 V so still rising but SN 2020qxp at 14.5 so probably sub-luminous near maximum as suggested by the TNS classifiers
SN 2020qxp is now also confirmed as a Ia and the classifiers suggest it should be near maximum light in which case it should in theory be approaching ~mag 11 excluding extinction in the parent galaxy. They also compare it though with SN 2007on which was classed as “transitional” (ie with a luminosity lower than normal for a 1a but more luminous than sub luminous 91bg-types). SN 2007on was considered a good candidate for a white dwarf merger supernova event eg
https://arxiv.org/abs/1802.09469
The light curve of SN 2020qxp could be interesting
Cheers
Robin
Hi Andrew,
If you untick the box that deletes the intermediate files, ISIS saves the individual profiles in a time series (as @pro_n.fit)
Cheers
Robin
Hi John,
There was an excellent detailed commentary on the evolution of nova spectra by Prof Steve Shore during the Nova Del 2013 ARAS campaign here
http://www.astrosurf.com/aras/novae/Nova2013Del.html
He has also issued an ATel on the current nova based on amateur spectra
http://www.astronomerstelegram.org/?read=13939
Cheers
Robin
