All the HOYS stacked images from the last few months in R, V and Ha, all stacked into one image and processed just for fun. No science left in it doing it like this, but a nice image anyway. I can find stars down to mag. 19.05 G-band from Gaia data.
Saw it outside and then found it on the meteor camera. Data from UKMON:
shower ID 7 PER (Perseids)
Lg 50.74° Bg 38.96° Vg 58.81km/s
mass 0.54304g, abs. mag -4.4
best visual mag -2.0
start -1.44° 55.83° 123.61km
end -1.97° 55.55° 85.49km
Semimajor axis 16.25A.U., eccentricity 0.94,
inclination 112.52°, Period 65.48Y,
LA Sun 128.41°, last Perihelion 2022-07-12
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 / 2022-07-20
Mag. 16.94 +- 0.09 / Mag. 12.33 +- 0.01
2022-07-11 23:49 UT 2022-07-20 23:04 UT
250mm f4.8 Newtonian, MPCC
Atik 460EX @-10°C
3 x 180s 2 x 180s d,f,b
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
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)”.
YSO (Young Stellar Object) Range approx: 12.3 – 13.9 Coordinates (2000): RA 16 39 06.43 Dec. +09 47 55.3
250mm f4.8 Newtonian MPCC
Atik 460EX @-10°C
5 x 60s d f b
“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).”
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.
DO Dra Typical/high state mag. 15.0 – 15.5 V Range: 10.0 – 17.2 V
23:00 – 23:59 UT
250mm f4.8 Newtonian
Atik 460ex @-10°C
70 x 60s dfb
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.
I’ve been continuing to gather HOYS data as normal and particularly focusing on this star as it’s a bit too low for most people in the evening, but high enough even when below the Pole Star from here in Edinburgh. A lot of the last few weeks data points are mine. Going back to the CCD camera and using real V and R photometric filters has increased accuracy to 0.02 – 0.04 as well.
The star has just undergone a new outburst and is starting to decline again.
The HOYS project reached another recent milestone of 60,00 images in the database. Unfortunately this means the database is now very slow to extract data for lightcurves for. Needs some funding for a developer to work on the database indexing.
2022hrs (= ATLAS22mip), TNS discovered 2022/04/16.619 by Koichi Itagaki Found in NGC 4647 at R.A. = 12h43m34s.350, Decl. = +11°34’36”.00 Located 30″.0 east and 18″.7 south of the center of NGC 4647 Galaxy is about mag. 12.5, supernova about mag. 14.1 R using photometry with ASTAP.
2022-04-18 23:20 UT
250mm f4.8 Newtonian R filter
Atik 460EX @-10 °C
3 x 180s d,f,b
Here’s the light curve from the BAA VSS database, including some of my observations (the very first red point – bottom left – is mine, as are some of the V CCD measurements).