AAVSO: American Association of Variable Star Observers

Proposal #252

Proposer (18434) Guy Stringfellow (Guy.Stringfellow@colorado.edu) obscode: SGUA
Assigned To(3663) Dirk Terrell
Date SubmittedJan. 13, 2022

We have an approved program for 2022A that will conduct a coordinated multi-facility optical-IR spectroscopic monitoring program to study the
formation/dissipation of Be-star decretion disks. Same night high-resolution optical spectroscopy will be obtained for 6 stars coordinated with
our IRTF IR spectroscopy being performed on several nights over the months of Feb-Mar. This will provide near-simultaneous continuous coverage
from ~3800A out to 2.5 microns. We request important light curve monitoring in BVri (or BVRI) starting immediately and running nightly into mid-April
(or when the stars set if before then). The extended cadence outside the specific spectroscopic monitoring is need to understand disk formation/dissipation
leading up to and after the spectroscopic monitoring. Ideally, scheduling on several BSM telescopes distributed over the network obtaining ~3 observations
in all filters over a 24 hour period, repeated nightly until mid-April. This would provide sufficient photometric time-variability in the light curve to determine
how the formation/dissipation of the disk evolves over this several month monitoring program. Photometric changes typically range from about 0.2-0.5 mag
from the no-disk (quiescent) state to peak disk formation during the events, so would like to achieve better than 1% photometry if possible. Two
advanced undergraduate students at CU Boulder (Rhiannon Harding and Amaranta Yanez) will be analyzing the BSM photometric light curves. We
are all AAVSO members, and are presently using VPhot and the tranformation curve fitting tools. We will need to establish comparison stars in each
field if not already available. We do have some questions that need addressing, such as whether all BSM telescopes have the same filter sets and if
these include the Astrodon B-filters with red leaks. Given we are studying massive hot stars (typically B stars) this may not be an important concern.
Note that we had requested and been allocated time to do (partial nightly ) monitoring using the LCOGT 0.4 telescopes but were advised given the
brightness of our stars that non-linearity affects will be present that are currently uncharacterized and uncorrectable. Hence, we anticipate the AAVSO
facilities will provide the light curves needed for the combined analysis. See e.g., Labadrie-Bartz et al. 2018, AJ, 155, 53 for an example of the importance
of the light curves used in our previous work of the analysis of Be-stars. Since this encompasses undergrad research work we are requesting a 1 year
proprietary period to allow the students to analyze and publish the results. We will then send the photometric results to the AAVSO archive database.
Please let us know if any further information is required.

Target RA (H.HH) Dec (D.DD) Magnitude Telescope Observation Frequency Expiration Date Proprietary Term
ABE-176 5.225638 38.10968 10.0–9.0 BSM_NH2 1 July 20, 2022 1 Year


(18434) Guy Stringfellow — Jan. 13, 2022, 10:25 p.m.

For some unknown reason only the first of 6 target stars listed printed out at my end after submission.
I can send these via email if they didn't go through. Thanks.

(3663) Dirk Terrell — Jan. 14, 2022, 3:56 p.m.

Yes, we're having trouble with the submission form processing. You can post the details of the targets as a comment and I'll include them in the message to the TAC.

(18434) Guy Stringfellow — Jan. 15, 2022, 1:10 a.m.

Here is the full target list:
Target RA DEC min Mag max Mag Proprietary
ABE-176 05:13:32.298 +38:06:34.86 10 9 1 year
ABE-097 05:16:46.742 +30:22:45.62 9 8 1 year
ABE-A24 05:18:10.181 +37:39:00.49 8 7 1 year
ABE-184 05:36:15.559 +32:57:14.56 10 9 1 year
ABE-027 05:45:37.134 +30:07:25.31 10 9 1 year
ABE-A26 05:25:44.784 +35:38:49.91 9 8 1 year

(3663) Dirk Terrell — Jan. 18, 2022, 8:47 p.m.

The TAC has approved this proposal but you need to submit the stars to VSX so that the eventual data can be uploaded. See


(18434) Guy Stringfellow — Jan. 19, 2022, 1:05 a.m.

Ok - I've registered in VSX and reviewed what exits or not on these 6 stars. One, ABE-A26 = HD35345, is already designated in VSX
with AUID=AUID=000-BBJ-278. Only 2 observations on this star (1984 and 2016) showing a 0.15 mag range. I think I am ready to
create entries for the other 5. Do I need to do this before observations begin? Or just before the time we eventually report the
photometry to the VSX database?

(3663) Dirk Terrell — Jan. 19, 2022, 1:10 a.m.

I believe it is sufficient to do it before the photometric data are submitted.

(3000) Sebastian Otero — Jan. 19, 2022, 1:40 a.m.

Yes Guy, get in contact with us when that time comes.
There is available documentation to help you with the process (including a manual) and we can guide you through it.

(18434) Guy Stringfellow — Jan. 19, 2022, 1:44 a.m.

Ok - thanks.

(4726) Kenneth Menzies — Jan. 21, 2022, 12:19 a.m.

Committed to NH, NM and TX

Comments on this proposal are closed.