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AAVSO Alert Notice 598
Intermediate polar FO Aqr fading and photometry needed now

September 6, 2017:  Dr. Colin Littlefield (University of Notre Dame) and colleagues have 
requested AAVSO assistance in monitoring the intermediate polar cataclysmic variable 
FO Aqr beginning immediately. This campaign is similar to the one on FO Aqr requested 
by Dr. Littlefield and colleagues in July 2016 (AAVSO Alert Notice 545).

Dr. Littlefield and co-authors Gordon Myers (AAVSO), Richard Sabo (AAVSO), Peter Garnavich 
(Notre Dame), and Mark Kennedy (University College Cork) recently published ATel #10703, 
and write therein that: "The intermediate polar FO Aqr, which in 2016 underwent the first 
low state in its observational history (Littlefield et al. 2016, ApJ, 833, 93), has faded by 
nearly 0.7 mag since 2017 August 10, implying a decrease in the system's accretion rate."

Good coverage of the current fading event - only the second observed in this system - 
is extremely important.

In an email Dr. Littlefield writes: "As with the previous campaign, we would like observers 
to obtain nightly photometric time series of FO Aqr. In order to maximize their usefulness 
to us, the observations would need to be either V-filtered or unfiltered with a V zeropoint 
(i.e., unfiltered but using the V magnitude of a comparison star when performing 
photometry, CV). We would like observers to use a cadence of 60 sec/image or faster, even 
if this means observing unfiltered, and we would prefer that each time series last at least an 
hour (preferably a minimum of 2 hrs). Our hope is that the AAVSO could observe FO Aqr 
until either (1) the end of the current faint state or (2) solar conjunction, which for FO Aqr 
is in January." Visual observations are also welcome.

He continues: "Because last year's fade began during solar conjunction, the drop to minimum 
went almost entirely unobserved. If this is the start of another deep low state like the 2016 
event, it would be the first opportunity to study how FO Aqr's accretion processes change 
during the drop to minimum. For example, AAVSO observations of the current fade by observers 
Gordon Myers and Richard Sabo have already provided important evidence of a correlation 
between FO Aqr's overall brightness and the mechanism by which material accretes onto 
the system's white dwarf.

"We had 16 AAVSO co-authors on our paper about the 2016 low state, and if observations 
from the new campaign lead to another publication, we would be pleased to offer co-authorship 
to AAVSO observers who contribute data used in our analysis."

Observations in the AAVSO International Database on 2017 September 2.6251 UT show 
FO Aqr at CV = 14.607 +/-0.010 (MGW, G. Myers, Hillsborough, CA). AAVSO data show 
that during the 2016 fading episode it was as faint as CV = 15.6. FO Aqr's brightness 
in its high state is V~13.4.

Coordinates (2000.0): R.A. 22 17 55.38  Dec. -08 21 03.8

Charts: Charts for FO Aqr with an expanded comparison star sequence may be created 
using the AAVSO Variable Star Plotter (VSP). For observers who have been following 
FO Aqr as part of the CBA program, the comparison stars used for that program have 
been retained.

Please submit observations to the AAVSO International Database using the name FO AQR.

This observing campaign is being followed on the AAVSO Campaigns and Observing 
Reports online forum at

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen.

AAVSO Alert Notice 597
GW Lib time set for third HST observation

September 6, 2017: Further to AAVSO Alert Notices 591, 595, and 596, 
Dr. Boris Gaensicke (Warwick University) informs us that the date and 
time for the third and final of three HST observations in his campaign on the 
pulsating white dwarf-containing cataclysmic variable GW Lib has been 
scheduled for2017 Sep 13 23:52:02 to Sep 14 04:30:12 UT.

Nightly snapshots are requested now through September 9, and intensive 
monitoring September 10 through 15, then nightly snapshots again through 
September 21.

Dr. Gaensicke reminds observers that the HST scheduling team will "...insist 
on a last quiescent measurement [V or positive visual] within 24h of the 
beginning of the COS observations, i.e. after UT Sep 12, 2017, 23:52."

As reported before, for the HST observations, AAVSO observations are essential 
to know the state of the system in order to ensure that the object is NOT in outburst 
when observed with HST. AAVSO observations made within 24 hours before each HST 
observing time will be used to make a go/no-go decision; data will be used in the 
analysis of the resulting data.

In addition to uploading observations to the AAVSO database, Dr. Gaensicke requests 
that all observations be sent to him by email at:

Coordinates:   RA: 15 19 55.45   Dec: -25 00 25.30   (J2000.0)

This target is increasingly challenging at this time of year, and your efforts are truly 
appreciated and are crucial to the HST observations.

GW Lib is faint at quiescence, magnitude ~16.8 visual/unfiltered. If visual observers 
are unable to detect GW Lib, please report any "fainter-than" estimates using the 
magnitude of the faintest comparison star magnitude seen. CCD observers are asked 
to use filters during observations if available; V filter is preferred, but B, Rc, and Ic 
may also be used. Detection of the variable itself is not required unless you can reach 
V=16.8 in reasonable time, but please use sufficient exposure to detect at least the 
V=143 comparison star (RA 15:19:39.54 Dec. -25:00:31.8) or V=147 
(RA 15:20:01.73  Dec. -24:58:37.7) with a S/N of 10 and report the observation as 
a "fainter-than" observation. GW Lib may be as bright as V=8.2 in outburst.

Beginning now, please observe this object as often as possible according to the 
schedule and using the observing procedure outlined above, and submit data 
as soon as possible to the AAVSO International Database using the name GW LIB.
During the nights of intensive observations as indicated above, prompt submission 
of your observations will be critical. In the event of an outburst, please contact 
the AAVSO immediately.

Charts with a comparison star sequence for GW Lib may be plotted using the 
AAVSO Variable Star Plotter (VSP).

This observing campaign is being followed on the AAVSO Campaigns and 
Observing Reports online forum at

Thank you for your observing efforts and valuable observations!

This AAVSO Alert Notice was prepared by Elizabeth O. Waagen.

AAVSO Alert Notice 588

Long-term CCD monitoring of ER UMa-type variable DDE 48 in Vulpecula

July 21, 2017: The following request for AAVSO assistance has been received from Denis 
Denisenko (Sternberg Astronomical Institute, Moscow State University) to help characterize 
"...the cataclysmic variable DDE 48 in Vulpecula. This CV belongs to the rare ER UMa subtype 
of dwarf novae, with only 6 other stars in VSX being classified as UGER. According to 2016-
2017 observations by Nikolay Mishevskiy (MNIC) and Denis Denisenko (DDE), this variable is 
very active, with superoutbursts to magnitude V=15.4 occurring approximately once a 
month.  There are several normal outbursts between the superoutbursts.

"The campaign has two goals: 1) to study the long-term behaviour (that is, determine the 
supercycle length and the exact number of normal outbursts per supercycle); 2) to measure 
the orbital period and to follow the evolution of superhumps period during the superoutbursts.

"Snapshot photometry (preferrably 2-3 times per night) is requested beginning now until the 
next superoutburst, which is about to start within the next 2-3 days. Observations from 
different longitudes are essential since the variable is changing very rapidly. When DDE 48 
brightens to magnitude V=16, continuous time series are requested for as long as possible 
while the object is above 30 deg elevation." DDE 48 is V=19.0-19.5 at minimum.

"Unfiltered observations are OK when the variable is below magnitude V=16. Use V filter only 
if you can reach S/N ratio of at least 50 in 60-sec or 90-sec exposures.

"Charts with a comparison star sequence for DDE 48 may be created using the AAVSO 
Variable Star Plotter (VSP). The recommended comparison star is the 146 on the AAVSO 
chart (V=14.573) and is located 3 arc min east of DDE 48, and the check star is the 156 
(V=15.605), which is 2 arc min east of DDE 48."

DDE 48 entry in AAVSO VSX: 

Coordinates: 20 46 11.80 +24 20 57.2 (J2000.0)

"Note: DDE 48 is located only 4 arc minutes west of another dwarf nova, MASTER OT 
J204627.96+242218.0, which has outbursts to V=15.5. Please take the opportunity to 
investigate these two poorly studied cataclysmic variables in one CCD field of view. The same 
comparison stars can be used for both CVs.

"A color-combined DSS finder chart showing the position of DDE 48 and MASTER OT 
J204627.96+242218.0 (10'x10' FOV) may be seen at: 

Please report your observations to AAVSO International Database using the name DDE 48.

This campaign, which will run through October 2017, is being monitored on the AAVSO 
Observing Campaigns webpage and is being followed on the Campaigns and Observation 
Reports Forum at

This AAVSO Alert Notice was compiled by Elizabeth O. Waagen from text supplied by Denis Denisenko.

It’s all about the  standstills, those episodes where the star gets stuck at a mid-point between maximum and minimum. If it doesn’t exhibit standstills it isn’t a Z Cam star.

Data from Catalina Real Time Survey 

Drake et al. 2009, ApJ, 696, 87

Northern CVs brighter than 17th magnitude here.

Southern CV's brighter than 17th magnitude here.


Last updated 16:13 UT on 22 September 2017

New outbursts and unusual activity reported in the last 72 hours


WY Tri

AT Cnc

AB Dra
CY Lyr
ASASSN-17mn (new discovery)
MASTER OT J231025.12+380037.5

Current superoutbursts (since ...)
WX Hyi (20170918)
SY Cap (20170916)
V344 Lyr (20170916)
NSV 2026 (20170916)
KV And (20170915)
V1454 Cyg (20170913)
ASASSN-17me (20170913; superhump period ~1.5 h)
PNV J20205397+2508145 (170912; Psh= 0.056528 d)
TCP J20100517+1303006 (201709212)
TY PsA (20170908)
ASASSN-13dh (20170908; superhump per. 0.09144 d)
TCP J231308.1+233702 (20170908)
AD Men (20170904)
ASASSN-17lr # (
20170904; UGWZ:)
V521 Peg (20170831; precursor on 20170824)
1RXS J161659.5+620014 (2070831)
NN Cam (20170830)
ASASSN-15qu (20170830)
CRTS J044027.1+023301 (20170830)
CTCV J1940-4724 (20170827)
MASTER OT J212624.16+253827.2 (20170825)
NSV 1440 (20170824; 3rd rebrightening 20170917)
ASASSN-17kd (20170729; rebrightening 20170903)
TCP J18154219+3515598 (20170602)

Z Cam-type dwarf novae at standstill
Z Cam (since 20170405)
IW And (20170812–20170831, 19 days)
OQ Car (20160415–20170826, 498 days)

# indicates a noteworthy or unusual outburst
:  indicates confirmation required
'Activity At A Glance' is gleaned from observations reported to AAVSO MyNewsFlash, BAAVSS-Alert, CVnet-Outburst, VSObs-share and VSNET-outburst. We sincerely thank all the observers who contribute timely observations and reports of activity to these email lists.


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