The potential of masers to act as probes of their environment has long been recognised, but to date has proven very difficult to realise. ... 2001, Sutton et al. 2001). Masers are variable on timescales of weeks to months and one of the major limitations in previous attempts at multi-transition analysis has been the uncertainties introduced by combining observations made over many years using a variety of instruments with differing spectral and spatial resolutions and polarisation properties. ...

... In order to compare the number of different evolutionary stages obtained and X-ray luminosity of the chosen X-ray sources with the observed galactic values we use the sum of C/O+O/C , where C and O are the calculated and observed values of a given binary type, respectively. If we make comparison for a number of different binary species (for example, we compare the number of CV, number of X-ray pulsars,   total X-ray luminosity of LMXB, etc.), we write this criterion in the form: . ...

Next: Radial velocity of the Up: Optical spectrum of IRAS04296 Previous: Observations and spectra reduction . ... However, molecular emission features are only very rarely observed in the optical spectra of PPNe. ... On the other hand, it is well known that cometary nuclei spectra show prominent Swan band emission. In both spectra of IRAS04296 we have discovered strong emission in the (0;0) and (0;1) bands of the Swan system of the molecule. ... Now consider the case of IRAS04296. ...

... the time of observation . ... Observing the Changing Position of the Sun To Establish Cardinal Directions . ... Observations of the Sun's apparent movement across the sky and its pattern of rising and setting in the east and west horizon helped to establish the cardinal directions. ... The final stage of the Sun's return was marked by the observation that the Sun had reached its highest altitude when the full width of your mitted hand could fill the gap between the Sun and the horizon. ...

... We will consider the rms, (K), for observations with a receiver of system temperature, T , frequency resolution, per polarization, and total integration time per observing cycle, . ... For ``in-band'' frequency switching, the line under investigation is always in the observing band. ... Position Switching or ``Out-of-Band'' Frequency Switching: Here the line is only observed for one half of the time, with noise being present all of the time. ...

These observations are aimed at fully charactering FORS1 photometric system (UBVRI zero-points, color-terms and extinction coefficients) for the Tektronix 2048x2048 pixel CCD (24µm px) . To this aim, the two Landolt/Stetson photometric fields SA95 and SA101 will be observed on a number of epochs and at different airmasses during February and March 2007. ... SA101 . ... OBs for SA101 have to be observed during evenigh twilight (exceptions are expected for the second half of March) . ...

This is the homepage of Andrew Fruchter, an astronomer on the staff of the Space Telescope Science Institute . ... Here you can look at an HST images of the optical counterparts of gamma-ray bursts and their host galaxies. ... Therefore, substantial information on the fine scale structure of objects can be obtained by offsetting the pointing of the telescope between exposures and then combining these "dithered" exposures into a single image. ...

Observation and modelling of main sequence star chromospheres. ... We compare our calculations to recent high res­ olution observations for selected stars in a narrow spectral range ((R­I) џ =0.875\Sigma0.05); we show that Hff line profiles behave as expected, with a tight correlation be­ tween the line width and equivalent width. ... We show that the hydrogen series dominate the radiative cooling in the spectral lines (form 40% to 90%) for Hff emission line stars. ...

ARCSAT ID NUMBER: AS04 DESCRIPTIVE TITLE: Short Term Variability for Stars of Similar Temperatures but Different Luminosities PI: Tiffany Clements (Pewett) (GSU) OBSERVER(S): Tiffany Clements (Pewett) (GSU), Michele Silverstein (GSU), Todd Henry (RECONS Institute) UNCERTIFIED/UNTRAINED OBSERVERS: COLLABORATORS: CONTACT INFORMATION: Tiffany Clements (Pewett), pewett@astro.gsu.edu, (419)460-0072 TIME REQUESTED: We request one week for the Q2 semester. ...

... The J, H and K bands are characterized by a bright background, such a background is mainly due to the emission of atmospheric lines and of thermal radiation. ... If the source cover a large fraction of the slit, spectra off-source must be observed to adequately sample the sky background. ... The on chip integration time (time spent in each position of the slit) must not exceed 40 seconds in J and H bands and 60 seconds in K band. ... We suggest a sequence of 10 for each elementary integration time. ...

Next: Reducing the observations Up: PEPSYS general photometry Previous: Influencing the plan . ... If the telescope and instrumentation are unfamiliar to you, you may have trouble keeping to the schedule for the first night or two, so try to work with a previous observer on the equipment for a night or two of training before your observing run. If you fall behind, try to keep as many low-altitude observations of extinction stars as you can, and drop some circumzenithal ones if necessary. ...