Brightening of Blazar BL Lac-type object S4 0954+65

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Hamish Barker
Posts: 226
Joined: Thu Jun 20, 2019 12:11 am

Brightening of Blazar BL Lac-type object S4 0954+65

Post by Hamish Barker »

https://www.astronomerstelegram.org/?read=15517

BL Lac-type object S4 0954+65
coordinates RA: 09 58 47.2452 Dec: +65 33 54.8194; ICRS J2000

Northern observers looking to stretch their spectroscopic distance limits might be interested to try this one:

"Since the beginning of April this year the BL Lac-type object S4 0954+65 (RA: 09 58 47.2452 Dec: +65 33 54.8194; ICRS J2000) has been showing increased activity both in the optical (ATel #15322; ATel #15344; ATel #15376; ATel #15380) - here also in polarized light (ATel #15414; ATel #15419) - and in the gamma-ray regime (ATel #15375).

In the optical the object reached new records in the R-band on 21 April - JD 2459691.24 with 13.20 mag (ATel #15344) as well as on 13 May - JD 2459712.6873 with 12.72 mag (ATel #15380).

In the following weeks the brightness decreased and moved in a range of about 14.7 to 15.8 mag (R-band).
Since 11 July the brightness of this object has been steadily increasing again and now has reached about 13.4 mag."

From a recent paper by Ahnen Et Al:
https://www.aanda.org/articles/aa/abs/2 ... 24-18.html

"This blazar has a disputed redshift of z = 0.368 or z ≥ 0.45 and an uncertain classification among blazar subclasses."

So perhaps more amateur spectroscopic observations could well add useful spectra to clarify the disputed redshift.

Cheers all,

Hamish
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