Variable Star

LZ UMi

2024-02-15T17:49:04+00:0015 February 2024|ASERO, Eclipsing Binary, News, Variable Star|

Data captured in Spain with ASERO-Murrell and here with my scope for this eclipsing binary.

Object IDLZ UMi
DetailsMurrell: 2024-02-05 01:06:09 ->
Forthimage: 2024-02-11 21:40:33 – >
TelescopeM: 300mm f4 ONTC Newtonian
F: 350mm f4.8 Newtonian
CameraM: Touptek IMX571 mono
F: AltairAstro IMX571 mono
FiltersV
Exposure(s)M: 54 x 120s
F: 58 x 120s
50% subframes
CaptureNINA
ProcessingASTAP, AstroImageJ

Markarian 421 Blazar

2023-04-28T15:31:32+00:0028 April 2023|Blazar, News, Variable Star|

Markarian 421 – which is actually a Blazar, at an easier than most mag. of 13.4, right next to a really faint galaxy (LEDA 33453) at mag 19.6. This one is only 411 million light years away.

Object IDMarkarian 421
Details2023-04-13 21:36 UT
Telescope250mm f4.8 Newtonian
MPCC
CameraATIK 460EX @-10°C
FiltersV
Exposure(s)5x180s
CaptureNINA
ProcessingAPP, ASTAP, Photoshop

UU Aql Dwarf Nova

2022-08-07T18:03:48+00:0022 July 2022|Cataclysmic Variable, Dwarf Nova, News, Variable Star|

X28087AF chart

Following the AAVSO campaign to observe some Dwarf Novae along with Hubble. The main aim is to determine when the star is faint enough for Hubble to observe it – to avoid damage to its sensors!

Alert Notice 758: Monitoring requested for 11 dwarf novae in support of HST observations in 2021-2022

Has had a recent outburst and my latest two measurements show it as V mag. 16.9 on 2022-07-11 and then on 2022-07-20 a V mag. of 12.3. Quite an outburst. Seems to happen every 2 months.

Photometry using ASTAP, plot from AAVSO VStar.

UPDATE: 2022-07-31 now very faint down at mag. 17 and on its base magnitude.

UU Aql 2022-07-11 Mag. 16.94 +- 0.09 / 2022-07-20 Mag. 12.33 +- 0.01

UU Aql 2022-07-11 / 2022-07-20

Mag. 16.94 +- 0.09 / Mag. 12.33 +- 0.01

Object IDUU Aql
Details2022-07-11 23:49 UT
2022-07-20 23:04 UT
Telescope250mm f4.8 Newtonian, MPCC
CameraAtik 460EX @-10°C
FiltersPhotometric V
Exposure(s)3 x 180s
2 x 180s
d,f,b
CaptureNINA
ProcessingASTAP, VStar

Dwarf Nova illustration

Credit: NASA and L. Hustak (STScI)

Current theory suggests that dwarf novae result from instability in the accretion disk, when gas in the disk reaches a critical temperature that causes a change in viscosity, resulting in a temporary increase in mass flow through the disc, which heats the whole disc and hence increases its luminosity. The mass transfer from the donor star is less than this increased flow through the disc, so the disc will eventually drop back below the critical temperature and revert to a cooler, duller mode. Wikipedia

V1117 Her

2022-07-22T10:19:37+00:0029 May 2022|News, Variable Star, YSO|

Taking part in the AAVSO campaign on V1117 Her: Alert Notice 771: V1117 Her in deep fade again. Comparisons marked in the main image.

The fade seems to be past but as well as long term variations it seems to be a star with short-term variations over periods of a few hours. An “…anomalous YSO (possibly debris-disc object)”.

Object IDV1117 Her
DetailsYSO (Young Stellar Object)
Range approx: 12.3 – 13.9
Coordinates (2000): RA 16 39 06.43 Dec. +09 47 55.3
Telescope250mm f4.8 Newtonian
MPCC
CameraAtik 460EX @-10°C
FiltersJohnson V
Exposure(s)5 x 60s
d f b
CaptureNINA
ProcessingASTAP

“The anomalous YSO (possibly debris-disc object) V1117 Herculis is at a deep minimum of visual magnitude 15.1 as of 2022 March 9.45 UT, from observations by AAVSO member John Pickett. Observations, in a variety of filters – visual observations included of course – are requested to see what happens next. Deep minima of this object have tended to occur at semi-regular intervals of about 400 days but the last comparable minimum drawn from the AAVSO light curve was only about 100 days ago, so this may indicate new processes are taking place in the circumstellar environment.”

“Observations in the B and I bands are especially welcome. V band photometry is encouraged, and visual observations are welcome. Observations two-three times per night are requested (and once per night between episodes of activity).”

DO Dra

2022-07-22T11:30:53+00:0012 May 2022|Cataclysmic Variable, Intermediate Polar, News, Variable Star|

AAVSO “Alert Notice 753: Monitoring requested for seven intermediate polars” – DO Dra (also known as YY Dra) is on the list, it’s circumpolar and easy from here.

“Photometry (V, CV) of the targets in the table below is requested. DSLR green and visual observations are welcome to supplement the light curves. The cadence requested is every other night, as weather permits, and “about one hour of coverage per night (enough to catch a few spin cycles of the white dwarf). If a source is found to be in a low state, then we request longer coverage and nightly cadence. SNR>>10 is ideal…”

Photometry (V, CV) of the targets in the table below is requested. DSLR green and visual observations are welcome to supplement the light curves. The cadence requested is every other night, as weather permits, and “about one hour of coverage per night (enough to catch a few spin cycles of the white dwarf). If a source is found to be in a low state, then we request longer coverage and nightly cadence. SNR>>10 is ideal…”

Covington adds: “These systems show periodic variability on the spin period of the WD, usually on order of ~10 minutes. So, shorter exposure times are needed so the spin variability isn’t washed out. Previous AAVSO observations of these sources have had exposure times <60s, which is ideal. Also, accurate time tagging of the observations is required, so we can measure periodicities!”

Thought I’d give it a go for 1 hour. Uploaded to AAVSO and BAA databases.

Object IDDO Dra
Typical/high state mag. 15.0 – 15.5 V
Range: 10.0 – 17.2 V
Details23:00 – 23:59 UT
Telescope250mm f4.8 Newtonian
CameraAtik 460ex @-10°C
FiltersV photometric
Exposure(s)70 x 60s
dfb
CaptureNINA
ProcessingASTAP

An Intermediate Polar (also called a DQ Herculis Star) is a type of cataclysmic variable binary star system with a white dwarf and a cool main-sequence secondary star. In most cataclysmic variables, matter from the companion star is gravitationally stripped by the compact star and forms an accretion disk around it. In intermediate polar systems, the same general scenario applies except that the inner disk is disrupted by the magnetic field of the white dwarf.

The name “intermediate polar” is derived from the strength of the white dwarf’s magnetic field, which is between that of non-magnetic cataclysmic variable systems and strongly magnetic systems. Non-magnetic systems exhibit full accretion disks, while strongly magnetic systems (called polars or AM Herculis systems) exhibit only accretion streams which directly impact the white dwarf’s magnetosphere.

Wikipedia

V1297 Cas eclipsing binary

2024-02-15T17:31:19+00:007 February 2022|Eclipsing Binary, News, Variable Star|

No predictions for transit times for this one so trial and error. Sadly missed both peaks and dips.

Object IDV1297 Cas
Eclipsing binary in Cassiopeia
Details2022-02-06
19:34 – 23:27 UT
Telescope250mm f4.8 Newtonian
Photometric V filter
CameraAtik 460EX @-10°C
Exposure(s)620 x 15s
darks, flats, bias
CaptureNINA
ProcessingAstroImageJ
V1297 apertures

NR CAM eclipsing binary

2024-02-15T17:31:26+00:0028 January 2022|Eclipsing Binary, News, Variable Star|

Got both secondary and primary transits before cloud came in but had hoped to get both peaks to see if asymmetric or not which might indicate star spots. Primary transit is deeper than the secondary.

Wrote a How-To article on the ASE website about this: How to record an eclipsing binary transit light curve

Object IDNR CAM
Eclipsing binary in Camelopardalis
Details2022-01-27
18:01 – 22:22 UT
Telescope250mm f4.8 Newtonian
Photometric V filter
CameraAtik 460EX @-10°C
Exposure(s)476 x 25s
darks, flats, bias
CaptureNINA
ProcessingAstroImageJ

Finder chart and data:
AAVSO — Variable Star Plotter

V523 Cas eclipsing binary

2024-02-15T17:31:34+00:0025 January 2022|Eclipsing Binary, News, Variable Star|

Cloud stopped play so caught the primary transit but not the secondary. Will try this one again since it transits so fast.

Object IDV523 Cas
Eclipsing binary star
Details2022-01-24
21:44 – 22:58 UT
Telescope250mm f4.8 Newtonian
CameraAtik 460EX @-10°C
Photometric R filter
Exposure(s)137 x 25s
darks, flats, bias
CaptureNINA
ProcessingAstroImageJ

AAVSO — Variable Star Plotter

PZ UMa eclipsing binary

2024-02-15T17:31:43+00:0018 January 2022|Eclipsing Binary, News, Variable Star|

Thought I’d try to catch an eclipsing binary transit since no obvious exoplanet ones to do for last night. First processed in HOPS, since that’s what I know, but that obviously wants to map an exoplanet transit onto the data. Finally processed in AstroImageJ, which charted it quite well.

Object IDPZ UMa
Details2022-01-17
21:18 – 00:12 UT
Telescope250mm f4.8 Newtonian
R Photomeric filter
CameraAtik 460EX @-10°C
Exposure(s)155 x 60s
darks, flats, bias
CaptureNINA
ProcessingAstroImageJ