Proposal #222

Comments

(3663) Dirk Terrell — July 27, 2021, 2:39 a.m.

Please give some more details about the targets, how you would like them to be observed, and a little bit about the scientific motivation.

(4697) Coliac Jean-Francois — Aug. 15, 2021, 2:24 p.m.

Dear Dirk

Here is a page on my website

http://www.astrosurf.com/jfcoliac/12_projet_BUR0.04/bur0.04.html with uploadable pdf files

These are very fast stars (less than one hour period and low magnitude around 15 and fainter)
So it is difficult to get good SNR with my 200mm

The time of observation would be ideally of 2 hours minimum or maximum (more than one cycle)

Few are catalogued from my study.
No data for YZ Lmi , KL Dra and CP Eri and very few on V406 Hya on LCG but valuable data on CR Boo
These faint stars are underobserved although they have very short period.

So I would like to do some measures...
Here is the project.

Cheers
Jean

(3663) Dirk Terrell — Aug. 17, 2021, 12:53 a.m.

Ok, then you would new to provide us with detailed observing information for each target such as

Filters to be used
Observing cadence and duration (of both time series during a night and for the project)
Which telescope to use

(4697) Coliac Jean-Francois — Sept. 23, 2021, 12:15 p.m.

Dear Dirk,

Sorry I forgot to read this mailbox.
For this season, KL Dra or ES Cet are good target.

Would it be possible to aim KL Dra, filter V during 2 hours (the period is 25 min) to catch 4 cycles.
The star is a difficult and challenging one mag 15,9 - 19,5 on VSX

More south target is ES Cet, filter V, during 45 min (period 10 min) to catch 4 cycles.
mag 16,5 - 17,1

A big scope would be suitable.

How works the acquisition ? I can control the scope ? or the images are done by another person ?

Many thanks
Science is fun
Jean

(3663) Dirk Terrell — Sept. 23, 2021, 9:16 p.m.

Ok, one reviewer had the following comments:

"these stars are mostly at their quiescent magnitude, so 17-20. CR Boo is the only exception. The proposer wants to look at the ~30min modulation, but doesn't specify the amplitude. I think most of these are in the 0.05-0.10mag range, which would imply photometric precision in the 0.01mag regime. At 18th magnitude with a 0.6m telescope, this takes 6 minutes at V under good conditions. That would give ~5 data points per cycle, minimal but doable. It would be better to do this with a clear filter, since you would have ~5x more throughput. Unfortunately, clear filters are hard to come by in the 60cm filter wheels! Sloan g would be an alternative, since it would have about 2x throughput. A further concern is that these are AM CVn systems, which are magnetic rotators. These usually have synchrotron radiation, which actually has highest modulation at R, so V or g might not be the best for some of these systems.

So I guess my question is what does the proposer want to obtain? If just a light curve that yields a basic modulation shape and period during quiescence, then unfiltered will work, and one night per star gives the basic information, and I think that we can do the project with one of the larger scopes."

Can you respond to that?

Comments on this proposal are closed.