Study of variable stars associated with maser sources: G025.65+1.05

We report variation of K-band infrared (IR) emission in the vicinity of the G025.65+1.05 water and methanol maser source. New observational data were obtained with 2.5m telescope of the Caucasian Mountain Observatory (CMO) of Moscow State University on 2017-09-21 during the strong water maser flare. We found that the IR source situated close to the maser position had decreased brightness in comparison to archive data. This source is associated with a massive young stellar object (MYSO) corresponding to the compact infrared source IRAS 18316-0602 (RAFGL 7009S). Similar decrease in K-brightness of the IR source close to the maser position was observed in March~2011 when the water maser activity was increased. The dips in MYSO brightness can be related to the maser flare phases. Maser flares that are concurrent with dips of the IR emission can be explained if the lower IR radiation field enables more efficient sink of the pumping cycle by allowing IR photons to escape the maser region.Comment: Accepted for publication in RA

Classification of bad pixels of the Hawaii-2RG detector of the ASTROnomical NearInfraRed CAMera

ASTRONIRCAM is an infrared camera-spectrograph installed at the 2.5-meter telescope of the CMO SAI. The instrument is equipped with the HAWAII-2RG array. A bad pixels classification of the ASTRONIRCAM detector is proposed. The classification is based on histograms of the difference of consecutive non-destructive readouts of a flat field. Bad pixels are classified into 5 groups: hot (saturated on the first readout), warm (the signal accumulation rate is above the mean value by more than 5 standard deviations), cold (the rate is under the mean value by more than 5 standard deviations), dead (no signal accumulation), and inverse (having a negative signal accumulation in the first readouts). Normal pixels of the ASTRONIRCAM detector account for 99.6% of the total. We investigated the dependence between the amount of bad pixels and the number of cooldown cycles of the instrument. While hot pixels remain the same, the bad pixels of other types may migrate between groups. The number of pixels in each group stays roughly constant. We found that the mean and variance of the bad pixels amount in each group and the transitions between groups do not differ noticeably between normal or slow cooldowns.Comment: 11 pages, 7 Figures, 3 table

Analysis of the interstellar matter at the periphery of the supershell surrounding the CYG OB1 association in 2.12 micron molecular hydrogen line

We present observations of the vdB 130 cluster vicinity in a narrow-band filter centered at a $2.12\,\mu$m molecular hydrogen line performed at the Caucasus Mountain Observatory of the Lomonosov Moscow State University. The observations reveal an H$_2$ emission shell around vdB 130, coincident with a bright infrared shell, visible in all \textit{Spitzer} bands. Also, numerous H$_{2}$ emission features are detected around infrared Blobs E and W and in the vicinity of a protocluster located to the east of the shell, in a tail of a cometary molecular cloud. H$_2$ emission in the vicinity of the vdB~130 cluster is mostly generated in well-developed \HII\ regions and is of fluorescent nature. In the protocluster area, isolated spots are observed, where H$_2$ emission is collisionally excited and is probably related to shocks in protostellar outflows. Obtained results are discussed in the context of possible sequential star formation in the vicinity of the vdB 130 cluster, triggered by the interaction of the expanding supershell surrounding the Cyg OB1 association with the molecular cloud and an associated molecular filament.Comment: Accepted by Astrophysical Bulleti