Proposal #181

Comments

(3663) Dirk Terrell — Jan. 11, 2021, 1:43 a.m.

Since ASAS-SN has several hundred visits to this field and only sees 5 variables down to 16th magnitude, the TAC does does not see a motivation for one night of observations of this field to search for variables down to 14th magnitude.

(38606) Gabriel Neagu — Jan. 11, 2021, 10:21 a.m.

But, is it possible to take another coordinates? And regarding ASAS-SN, they aren't that good at low amplitude variable stars, so there could still be variables. For example, in my latest approved proposal, i found a new variable star of DSCT type. Even though ASAS-SN data were good to refine the period and the range, they didn't recognize it as a variable. The new star found with AAVSOnet is called now NGCA-V61 in VSX.

(2108) Arne Henden — Jan. 11, 2021, 12:54 p.m.

Hi Gabriel,
Both beta Cep and delta Sct variables are galactic disk variables, and as such are unlikely to be found in this high galactic latitude field. They also tend to have amplitudes of only a few hundredths of a magnitude, and so might be seen if they were bright, but at 14th magnitude, you would need much deeper exposures in order to get adequate signal to noise. As a final point, these low-amplitude variables will mostly be found by TESS, as they are periodic and so easily seen in that satellites' precise, all-sky, photometry. The field you chose, because it is high galactic latitude, also has few stars to inspect.

I realize the attraction in discovering new variables, but it is much harder to do today than, say, a decade ago. Most of the newly discovered variables are transient objects: supernovae, novae, new cataclysmic variables, etc. These would not be found in a single night of time-series photometry as you were requesting. That said, I don't have strong objections to devoting a night on one of the southern BSMs, but suggest that you look around and find a mid-latitude field where there might be ~1000 measurable stars, but not so crowded that you get many blends.

(2108) Arne Henden — Jan. 11, 2021, 2:04 p.m.

In fact, the best way to get TAC approval is to either (a) request a time series of a known variable, and then look in the field for other variables, as you did for your DSCT; or (b) work with another researcher who has already done a time series on some variable, and use those images to search for new variables. Otherwise, you are requesting several hours of telescope time with low probability of success, and even if you find a variable or two, the scientific return of one more DSCT is low.

(38606) Gabriel Neagu — Jan. 11, 2021, 3:27 p.m.

In this case, I'd do star WISE J012225.7-653933. It is located at 01 22 25.74 -65 39 33.6. It's an EW and I'd like to use the data to refine de data and range. And also search for new variables around

(2108) Arne Henden — Jan. 11, 2021, 3:40 p.m.

The binary doesn't have any current AAVSO photometry, so in that sense, is a good target. However, as the current LST at twilight is about 4hrs, this field is already far in the west and can only be observed for 3-4 hours. The observing window would only cover about 1/2 of the 7.1hr period of the star. Its V magnitude is unknown (VSX only gives the W1 magnitude in the infrared), but looks about 12th on the DSS chart. However, note that the galactic latitude is -51 degrees, and the field is sparse, so I'm not sure how many new variables you will find. However, if you want to choose this, I'd suggest submitting another proposal so as to keep things consistent. No guarantees regarding TAC approval. Thanks!

(38606) Gabriel Neagu — Jan. 11, 2021, 4:52 p.m.

Ok. Thanks! I'll do another proposal in a more populated and useful zone for both purposes

Comments on this proposal are closed.