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I recorded and stacked 34 min of Rc images of PV Cep last night, 22nd October. These show that PV Cep was slightly fainter than the previous month at Rc = 17.24 and that the northern part of Gyulbudagian’s Nebula remains faint while the southern part is brighter than I remember seeing it for a long time. The southern part of the surrounding molecular cloud may be becoming more transparent as it seems less likely that changing illumination from PV Cep is the cause.
David
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Hello David,
This could be because you are trying to measure a very faint spectrum and ISIS is failing to detect the spectral trace in each image. If that is the case you should tick the box labelled Fixed Y value for sequence in the General tab and untick the box labelled Vertical coordinate Auto in the Calibration tab. Then manually adjust the contrast sliders at the bottom to make the spectrum visible in the Calibration tab and manually position the dotted red line in the Graticule over the spectrum. Then press Go and it should correctly locate the spectrum in each image and measure it correctly.
This assumes your guiding is good enough to keep the star at the same position in the slit (which corresponds to the Y coordinate in the calibration window). If the star is too faint to guide on successfully then the spectrum may be at a different Y coordinate in each image and the above recipe will not work. In that case you may have to put the target in the slit manually then guide on a brighter star in the guider window.
Hope that helps.
DavidHi Robin,
There were 3 under 16 places left so I asked Maddy in the office to change these to adult places. There are now 3 places available – book soon to avoid disappointment. 🙂
Regarding live streaming we have to discuss this with RAL on whose premises the meeting is being held.
Cheers,
DavidObserving 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
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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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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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
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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.
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
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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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.
DavidPlease 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.
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
Could be the formation of optically thick dust similar to what happened with Nova Cas 2020 (=V1391 Cas).
David
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
Or possibly dredged up?
A beautiful example of what can be achieved with high quality equipment and very compliant weather!
DavidThe 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
