Wed, 10/23/2019 - 18:16
Hello,
I was wondering if it was possible to find out how much time on one of the BSM telescopes is unallocated. The particular one we might be interested in using is BSM_South. We ran a high resolution spectrographic campaign on the delta Scuti star Sig Oct ealier this year. We did not have photometry data taken at the same time, but looking ahead if we were to run a second campaign we would like to get photometry. its brightness (M_v=5.45) is such that it would probably suit the capabilities of the BSM but would require substantial chunks of observing time over the period of the campaign. Before we write up a proposal we'd like to know if such a request is likely to adversely impact other users.
Thanks for any guidence.
Bill Rea
Bill:
Can you give some idea how much time you are looking for. delta scuti's are fast so would 2-3 hours on a given night be ok? Or longer to get more periods? Should not be a problem as long as it is not >100%!
Probably best to put it on both AU scopes to speed it up since one may be cloudy but the other not. How many nights to replicate? One or more?
Ken
Ken,
At this stage we're just thinking ahead. During the spectroscopic observations we were taking spectra for up to about 6.5 hours per night over two periods of two weeks seperated by a month. What we were thinking was to have some photometry from before the spectroscopic campaign, say two to three weeks, so we know which frequencies are the strongest. Given the frequencies we have seen in the data, we would need a minimum of 3 hours a night. Then match spectrographic and photometric observing as much as is practical during the spectrographic observing run. We realise this would place high demands on obseving time so really we just want to know if the BSM have enough unallocated time to do this. Currently we don't have an observing campaign in the planning, but are just trying to work out how to get photometric and spectroscopic data as close to simultaneously as prcatical.
Bill Rea
Hi Bill and Ken,
I'd be interested in contributing photometry of Sig Oct. From my -30 degree lattitude it's visible throughout the night and my small photometry rig can comfortably work at that magnitude. One issue will be finding suitable Comp and Check stars in the field of view. Next clear night I'll record a time series over several hours and see what the light curve looks like. What cadence are you looking for? Cheers,
Mark
Mark,
We found periods as short as about 30 minutes in the spectroscopic data so taking 10 sample points per cycle as a reasonable rule of thumb that would require a measurement about once every three minutes. I checked the availability of comparison and check stars a few days agao and currently there is nothing close enough that Sig Oct and current comparisons the would be in the same field of BSM_South. I haven't put in a request to the comparison star team for the addition of suitable stars, so if you want to try obseving Sig Oct, you would need to ensure comparisons get added, assuming you use VPHOT.
The dominant photometric period is usually about 2 hours 17 minutes (10.49 cycles/day), but the pulsations change over time and using data from a paper by Crouzet and co-authors that period weakens occastionally. From the Crouzet data the 10.49 c/d frequency was the strongest frequency in 2008, 2009 and 2010 but in 2010 it had weakened considerably and in their 2011 data it had dropped down to be the 14th strongest frequency. Observing detla Scutis takes a lot of observing time. If you're interested in our results so far I can email you a copy of my project final report.
Bill Rea
Hi Bill,
thanks for the details, I'd appreciate a copy of your project final report. I'll contact you off-line. Cheers,
Mark
I just added two comps (79 & 81) within a 90 arcmin chart that you can narrow down by off seting.
Caution, I note that this target (Sig Oct) has a very close star due west... you might use Aladin to zoom in on the target to see this. With such a small target variation (.05) this close star may affect data, depending upon whether included or not within the annulus of observers.
Be carful that you do not saturate this bright target. All digital observers should know and test the linearity of their equipment.
Ad Astra,
Tim Crawford, Sequence Team
Tim,
Thanks for adding those two comparison stars.
Bill Rea