[David Boyd]

Observing statistics for 2023

According to my records 2023 was another poor year here in South Oxfordshire, the sixth in a pattern of slowly decreasing availability of clear skies. I record the number of nights on which I was able to make at least one photometric observation as a percentage of the number of nights when I was at home and potentially able to observe if sky conditions permitted. I think this is a fair estimate of the percentage of observable nights in the year.

In 2023 that was 86 nights out of 279 = 30.8% (2022 35.8%). This makes 2023 the worst year since I started keeping records in 2005. The best months were January, February and June, the worst March (7%), December (12%) and October (22%). During 2023 I made 206 photometry runs on specific targets comprising 17187 measured images. I also recorded 97 spectroscopy runs with 1424 spectra measured.

David

[David Boyd]

Hi Grant,

Good idea. I’ll work on it in the New Year.

David

[David Boyd]

This image of Gyulbudaghian’s Nebula recorded on 19th December 2023 is 23 mins of integration with a 0.35m SCT at F/5 and Rc filter. It shows the core of the nebula is slightly brighter than it was in my post a few months ago.

David

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   PV-Cep-2023-12-19.jpg
   

[David Boyd]

This LISA spectrum of T CrB taken on 4th September shows that emission lines other than H alpha and to a lesser extent H beta have disappeared at this resolution.

David

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   tcrb_20230806_895_D_Boyd.png
   

[David Boyd]

This image taken on 14th August 2023 shows the nebula has brightened considerably since I last imaged it on 12th July. It is a stack of 29 x 60 sec images with an Rc filter on an 0.35m SCT under good conditions. The bright stars in this stacked image are saturated. I measured the mean Rc magnitude of PV Cep from the individual images as 16.93 +/- 0.05.

David

• This reply was modified 8 months, 1 week ago by David Boyd. Reason: Date on attached image corrected!

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   PV-Cep-2014-08-14.jpg
   

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   PV-Cep-2023-08-14.jpg
   

[David Boyd]

Observing statistics for 2022

According to my records 2022 was another poor year here in South Oxfordshire. I record the number of nights on which I was able to make at least one photometry observation as a percentage of the number of nights when I was at home and potentially able to observe if weather permitted. I think this is a fair estimate of the percentage of observable nights in the year.

In 2022 that was 102 nights out of 282 = 35.8% (2021 35.5%). The best months were March and August, the worst September and December. Plots of these percentages by month for 2022 and annual percentages from 2005 to 2022 are attached.

During 2022 I made 311 photometry runs on specific targets comprising 17002 measured images. This included several multi-hour runs observing flare stars. I also recorded 130 spectroscopy runs with 2932 spectra measured.

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   Percentages-by-month-2022.png
   

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   Percentages-by-year.png
   

[David Boyd]

Hi Grant,

My attempts to image the nebula earlier in the autumn have been affected by either thin cloud, haze or moonlight making the nebula barely detectable. This was a really clear night here and the extended E wing of the nebula was more prominent than I had seen it for most of 2022. Trying to measure the flux from the nebula is still problematical. I can only detect a very slight increase in both PV Cep and the nebula.

David

[David Boyd]

Here is a 35 x 60 sec stack of clear filtered images of the field. The SN is clearly visible still.

David

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   ZTF22aaylnhq.png
   

[David Boyd]

BX Mon is reported to be an eclipsing symbiotic binary with an orbital period of ~3.5 years. It comprises a hot component, probably an A/F type star and a cool red giant. The light curve is complex but the recent increase in brightness is likely due to the hot component emerging from eclipse.
David

[David Boyd]

Please put the list of recent Forum posts back on the home page. It is always the first place I look when going to the website.

And can it be made to remember my login so I don’t have to do this every time I visit the website.

[David Boyd]

2021 was statistically one of the poorest years for observing since I started recording this in 2005. I calculate my results on the basis of the number of nights I was able to record useful data relative to the number of nights I was at home and potentially able to observe, so it is a measure of the fraction of observable nights in the year. My average for the year was 35.5% based on 118 nights out of 332. The best months were April and September, as they usually are, and the worst were January, November and December, again as usual.

Best wishes for clearer skies in 2022.

David

[David Boyd]

Could be the formation of optically thick dust similar to what happened with Nova Cas 2020 (=V1391 Cas). 

David

[David Boyd]

Hi Robin,

Thanks for your kind comments but I’m not sure it justifies such fulsome praise! It was an interesting project to study the behaviour of these stars in a way which is unlikely to be carried out by professional astronomers because it involves committing resources and maintaining regular observations over years. Amateurs on the other hand are well placed to carry out this sort of project.

David

[David Boyd]

Or possibly dredged up?

https://arxiv.org/pdf/astro-ph/9803121.pdf

[David Boyd]

A beautiful example of what can be achieved with high quality equipment and very compliant weather!
David

[David Boyd]

The continuum flux level of the spectrum is dropping as the magnitude fades, V=4.88, 5.44, 6.24 for the 3 spectra below.

In answer to Hugh’s question above about the changes which have been taking place in the Balmer emission lines, I have posted information about this on the ARAS Forum at 

http://www.spectro-aras.com/forum/viewtopic.php?f=36&t=2804&start=30#p15940

David

[David Boyd]

Here is a spectrum of RS Oph in outburst taken tonight, 9th August, with a LISA. Very sharply peaked H-alpha line with FWZI of about 7000 km/s. Other Balmer lines similarly broad, all with P Cygni absorption dips. I don’t remember seeing a spectrum quite like this before!

David

[David Boyd]

Here is a spectrum of Nova Cas 2021 taken on 6th August with a LISA (R~1065) and calibrated in absolute flux using a concurrently measured V magnitude of 7.70. There are broad emission lines of H I Balmer and He I, all with P-Cygni absorption dips, and weak Fe II emission lines with double peaks. The H-alpha line is so strong that exposures had to be kept to 40 sec to avoid saturating. Further information about the spectrum and more plots can be found on the ARAS Forum at

http://www.spectro-aras.com/forum/viewtopic.php?f=36&t=2744&p=15888#p15888

David

[David Boyd]

Last night, 3rd August, I measured Nova Vul 2021 at V=10.97, B-V=1.14, almost a magnitude fainter than 48 hrs before and slightly redder. As Robin said, there has been a big change in the spectrum over recent days.

The following LISA spectrum (R~1062) was calibrated in absolute flux using this V magnitude and response corrected with the B9III MILES star HD192907 recorded at the same airmass as the mid-time of the nova spectrum. H-alpha has a strong P-Cyg absorption dip at -320 km/s which now falls within the much broader ~3000 km/s FWZI of the line. FeII multiplets 42, 49 and 74 are prominent with just-resolved P-Cyg dips. There are also emission features at ~5526A, ~5662A and ~7117A, all with P-Cyg dips, which I have not been able to identify in the WIlliams list of nova emission lines. Suggestions?

David

[David Boyd]

I confirm what Robin reported above that the emission cores of the Balmer lines have progressively disappeared over the past 4 days. The spectral profile and flux of the star are now very similar to what they were on 15th July shortly after the outburst was detected.

David

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