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The source G9.62+0.20E surprises again! Several of the associated 6.7- and 12.2-GHz methanol masers are experiencing contemporaneous and systematic velocity drifts. Both 6.7- and 12.2-GHz methanol features blueward of v = +1.2 km s−1 are blue shifting while those redward are red shifting. A best-fitting rotating Keplerian disc with a central mass of ∼12 M⊙, radii Rinner = 5 au and Router = 5000 au, and at an inclination angle of 22○ either precessing and/or experiencing infall explains these systematic velocity drifts. Also three more distinct 6.7-GHz methanol maser features are found to vary periodically; two very weak and one obviously periodic only after 2003. Evidence of periodicity is seen as early as 1992. Time lags are confirmed but the cause is unclear. It is possible this source will surprise again.

Ten new class II methanol masers from the 6.7-GHz Methanol Multibeam survey catalogues III and IV were selected for a monitoring programme at both 6.7 and 12.2 GHz with the 26m Hartebeesthoek Radio Astronomy Observatory (HartRAO) radio telescope for two years and nine months, from August 2012 to May 2015. In the sample, only masers associated with G339.986-0.425 were found to show periodic variability at both 6.7 and 12.2 GHz. The existence of periodic variation was tested with four independent methods. The analytical method gave the best estimation of the period, which was 246 $\pm$ 1 days. The time series of G339.986-0.425 show strong correlations across velocity channels and between the 6.7 and 12.2 GHz masers. The time delay was also measured across channels and shows structure across the spectrum which is continuous between different maser components., 13 pages, 18 figures, 4 tables, accepted for publication in MNRAS. The appendix of 6 pages (with 22 figures) will be published as online version

The Antlia Cluster is a nearby, dynamically young structure, and its proximity provides a valuable opportunity for detailed study of galaxy and group accretion onto clusters. We present a deep HI mosaic completed as part of spectral line commissioning of the Karoo Array Telescope (KAT-7), and identify infrared counterparts from the WISE extended source catalog to study neutral atomic gas content and star formation within the cluster. We detect 37 cluster members out to a radius of ~0.9 Mpc with M_HI > 5x10^7 M_Sun. Of these, 35 are new HI detections, 27 do not have previous spectroscopic redshift measurements, and one is the Compton thick Seyfert II, NGC 3281, which we detect in HI absorption. The HI galaxies lie beyond the X-ray emitting region 200 kpc from the cluster center and have experienced ram pressure stripping out to at least 600 kpc. At larger radii, they are distributed asymmetrically suggesting accretion from surrounding filaments. Combining HI with optical redshifts, we perform a detailed dynamical analysis of the internal substructure, identify large infalling groups, and present the first compilation of the large scale distribution of HI, and star forming galaxies within the cluster. We find that elliptical galaxy NGC 3268 is at the center of the oldest substructure and argue that NGC 3258 and its companion population are more recent arrivals. Through the presence of HI and on-going star formation, we rank substructures with respect to their relative time since accretion onto Antlia., 22 pages, 12 figures. Accepted for publication in MNRAS

We present the light curves of the 6.7 and 12.2 GHz methanol masers in the star forming region G9.62+0.20E for a time span of more than 2600 days. The earlier reported period of 244 days is confirmed. The results of monitoring the 107 GHz methanol maser for two flares are also presented. The results show that flaring occurs in all three masing transitions. It is shown that the average flare profiles of the three masing transitions are similar. The 12.2 GHz masers are the most variable of the three masers with the largest relative amplitude having a value of 2.4. The flux densities for the different masing transitions are found to return to the same level during the low phase of the masers, suggesting that the source of the periodic flaring is situated outside the masing region, and that the physical conditions in the masing region are relatively stable. On the basis of the shape of the light curve we excluded stellar pulsations as the underlying mechanism for the periodicity. It is argued that a colliding wind binary can account for the observed periodicity and provide a mechanism to qualitatively explain periodicity in the seed photon flux and/or the pumping radiation field. It is also argued that the dust cooling time is too short to explain the decay time of about 100 days of the maser flare. A further analysis has shown that for the intervals from days 48 to 66 and from days 67 to 135 the decay of the maser light curve can be interpreted as due to the recombination of a thermal hydrogen plasma with densities of approximately $1.6 \times 10^6 \mathrm{cm^{-3}}$ and $6.0 \times 10^5 \mathrm{cm^{-3}}$ respectively., Comment: 11 pages, 9 figuers

The class II methanol maser source G9.62+0.20E undergoes periodic flares at both 6.7 and12.2 GHz. The flare starting in 2001 October was observed at se ven epochs over three monthsusing the VLBA at 12.2 GHz. High angular resolution images (beam size ∼ 1.7 x 0.6 mas)were obtained, enabling us to observe changes in 16 individual maser components. It wasfound that while existing maser spots increased in flux densi ty, no new spots developed andno changes in morphology were observed. This rules out any mechanism which disturbs themasing region itself, implyingthat the flares are caused by a change in either the seed or pumpphoton levels. A time delay of 1–2 weeks was observed between groups of maser features.These delays can be explained by light travel time between maser groups. The regularity ofthe flares can possibly be explained by a binary system.Key words: masers – HII regions – ISM: clouds – Radio lines: ISM – stars: f ormation 1 INTRODUCTIONClass II methanol masers appear to be closely associated withthe earliest evolutionary stages of high mass stars (Menten 2002;Minier et al. 2003, and references therein). In many cases, themasers at 6.7 or 12.2 GHz are the only indication of star forma-tion activity at a particular site (Walsh et al. 1998; Goedhart et al.2002). Thus methanol masers are excellent probes of the changingconditions in the vicinity of young (proto)stars.The prevalent model for class II methanol masers is theSobolev-Deguchi model (Sobolev & Deguchi 1994; Sobolev et al.1997). This model has recently been further refined to exam-ine in detail the large number of methanol maser transitions ob-served in star-forming regions (e.g. Cragg et al. 2001). Themodelof Sobolev et al. (1997) is the only one which has been able toreproduce the high brightness temperatures (>10

A sample of 54 6.7-GHz methanol masers was monitored using the Hartebeesthoek 26-m telescope during the period 1999 January – 2003 March. The observations were taken at 1–2 week intervals, with daily observations when possible if a source was seen to be varying rapidly. It was found that the majority of the sources display a significant level of variability. The time-range of variations range from a few days up to several years. The types of behaviour observed included non-varying, monotonic increases or decreases, as well as aperiodic, quasi-periodic and periodic variations. Seven sources show clear evidence of periodicity, with periods ranging from 132 d up to 520 d.

Class II methanol masers are believed to be associated with high-mass star formation. Recent observations by Walsh et al. and Phillips et al. reported a very low detection rate of radio continuum emission toward a large sample of 6.7-GHz methanol masers. These results raise questions about the evolutionary phase and/or the mass range of the exciting stars of the masers. Here we report the results of a VLA search for 8.4-GHz continuum emission from the area around five Class II methanol masers, four of which were not detected by Walsh et al. at 8.6 GHz. Radio continuum emission was detected in all five fields although only two of the nine maser spot groups in the five fields were found to be superimposed on radio continuum sources that appear to be ultra-compact H II (UCH II) regions. This suggests that continuum counterparts for some masers might be found in further surveys for which the sensitivity level is lower than 1 mJy beam - 1 . Considering our results as well as observations from other studies of methanol masers we conclude that masers without radio continuum counterparts are most likely associated with high-mass stars in a very early evolutionary stage, either prior to the formation of a UCH II region or when the H II region is still optically thick at centimetre wavelengths. With one exception all maser spot groups in the five fields were found to be associated with mid-infrared objects detected in the Midcourse Space Experiment survey.

The class II methanol maser source G9.62+0.20E has been monitored since 1999 at 6.7 GHz and since 2000 at 12.2 GHz. Six flares have been observed to date. These flares are periodic, with an interval of 246 d between flares. The duration of the flare is approximately 3 months, with maximum amplitude reached a month after the start of the flare.

Near-infrared (NIR) images at I, J, H and K bands were made of 12 southern 6.7-GHz methanol maser sources. Astrometry accurate to 0.5 arcsec was obtained. The positions of known H II regions, water masers, hydroxyl masers, and mid- and far-infrared objects in the region are examined in order to try to determine the nature of the methanol maser source. Deeply embedded NIR sources were found close to seven out of 14 maser sites. In three cases, no NIR source, H II region, water maser or hydroxyl maser could be found in likely association with the methanol masers.

Near-infrared photometry was performed on 56 southern 6.7-GHz methanol maser sources. A simple spherically symmetric model of the radiative transfer through a dust shell was developed and used to study the conditions in the dust cloud in which the masers are produced. The parameters investigated were the size of the cloud, the spectral type of the embedded star, the optical depth of the dust cloud and the dust density distribution. It was found that the infrared colours of the models have a complex dependence on the parameters and that no unique combination of parameter values explains the spectral energy distribution of any particular source. The model effectively reproduces the far-infrared (IRAS) colours but cannot simultaneously explain the near-infrared colours for any of the observed sources.