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ASASSN-14ja observations needed

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Sebastian Otero
Sebastian Otero's picture
ASASSN-14ja observations needed

ASASSN-14ja is the latest CV discovered by the ASASSN team.

The identification is uncertain because "ASAS-SN photometry is contaminated by a nearby bright star", acording to the ASASSN transient page.

They also say that the candidate "matches to a B=15.8 blue star" but that is not consistent with the observations. No 15.8 blue star around the bright star, and the bright star itself has B= 14.7.

The combined magnitude is given as 13.1V at maximum on October 14.
The position reported is that of the 14.2 magnitude star GSC 09301-00992 (V= 14.19; B-V= 0.48, according to APASS).

Subtracting the contribution of the 14.2 mag. star the variable would be at V= 13.6.

Can anyone properly identify the outbursting object and measure a position?

DSS images show a faint candidate only included in the AllWISE catalogue (WISEA J175607.64-745944.8) 12" to the West of the 14.2 mag. star. It is at 17 56 07.65 -74 59 44.87 (J2000.0).


Sebastian Otero
Sebastian Otero's picture
ASASSN-14ja info

This is the VSX entry with the currently reported data:


WGR's picture

Hello Sebastian

You had me hooked, until the Dec of -74.



pukemaru's picture

Sebastian, are we going to get a visual sequence for this?
Stephen [HSP]

mgw's picture
ASASSN-ja Measurements

At UT 2014-10-17  09:07:24 in Siding Spring I measured the following for ASASSN-ja using the comps in VSX:

Vmag = 14.309 with an error or .009

Bmag = 14.784 with an error of .009

(these are not transformed)

The locaton measurements for the target on the two images (using VPHOT) were -

Image 1 (V) -  RA = 17:56:10.48     Dec = -74:59:45.24

Image 2 (B) -  RA = 17:56:10.51     Dec = -74:59:45.47

The data has been submmitted.

I can share the images via VPHOT if anyone wants to see them - just send me you observer id.

I don't really see the new star as of now...  This looks like the old one you refer to.



mgw's picture
asassn-ja not accepting measurments

I tried to upload my measurement but apparently ASASSN-ja is not in VSX...

Sebastian Otero
Sebastian Otero's picture

Hi Gordon,

>>> I tried to upload my measurement but apparently ASASSN-ja is not in VSX...

It is ASASSN-14ja, you were omitting the 14.

Interesting that you found no star other than the 14.2-14.3 bright companion.
Maybe the outburst has already faded to a level when the CV does not contribute to the combined brightness if it happens to be too close to be resolved.
Or maybe it was some kind of event in the 14th mag. star itself?

The position of the 14th mag. star is 17 56 10.77 -74 59 44.2 (J2000.0, UCAC4)


mgw's picture
ASASSN-14ja image

jpeg of the image is attached.  Looks clean right now.  I'd guess a transient, but don't know what might cause one of the magnitude increase reported.


HQA's picture

I've added it to the OC61 queue, where it is currently cloudy and 50mph winds.  It will get observed on the next clear night, unless someone else has the opportunity before it does.


CTX's picture
Sequence Is Now Available

A sequence is now available for ASASSN-14ja

Tim Crawford, CTX, Sequence Team

Sebastian Otero
Sebastian Otero's picture
ASASSN-14ja is an RRAB-type star

Even when the 13.2 mag. star partially contaminates ASAS-3 data, I decided to check the data anyway because I suspected it could be an RRAB caught at maximum by ASASSN.

SPM4.0 gives V= 13.32 for the suspect and the colors look okay for an RRAB.

Two observations from APASS give 14.19 but they are spaced by almost exactly 1 day and an RRAB with a 0.5 d. period would look constant.

And that was indeed the case!

It is an RRAB with a period of 0.498256 d.

This is the ASAS-3 light curve.

I will update the VSX entry after correcting for the light contamination.

Best wishes,


Sebastian Otero
Sebastian Otero's picture
Good work!

Thanks Gordon for taking a look.
Your image clearly showed no transient close to the 14th mag. star and this prompted the analysis of the available data.

I have now corrected the VSX entry with the new information.
Your data point is included in the phased light curve.
The two APASS observations one day apart are on top of each other.


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