![active sky next or as16 active sky next or as16](http://www.f-bmpl.com/files/ASN/CONFIG.jpg)
The basic promise of the series is well known: insert realistic and real-time weather into our flight simulators. Hifi Tech’s Active Sky series has been around a long time. Concurrently, Hifi Tech released an accompanying product: Active Sky Cloud Art. The pipeline bins the data to 1024 × 1024 format during calibration so that the pipeline output calibrated images are native format (see the STIS Data Handbook for more details).July 2016 saw the release of the latest in a long line of Active Sky products. However, we note that data taken in highres mode can always be binned to 1024 × 1024 on the ground in post-observation data processing, and since the extra overheads in highres mode are typically quite small, highres is the default data-taking mode for the MAMA.
#ACTIVE SKY NEXT OR AS16 FULL#
This effect and the inherently lower signal-to-noise ratio in the full resolution flat-field images (nominally ~20 to 1 per highres pixel) suggest that it may be difficult to routinely realize the benefit in resolution. The highres flat fields have much more structure than the 1024 × 1024 flats, with adjacent columns and rows differing by ~30% in an off/on pattern whose variability is appreciably higher than for 1024 × 1024 format images. The gain of the highres 2048 × 2048 mode is a ~10–30% increase in resolution at the price of the increased fixed-pattern noise due to poorly characterized charge partition among the electrodes. However, each count is detected by multiple electrodes, so the charge distribution among the electrodes can be used to centroid the incident charge cloud to subpixel resolution. The MAMA detectors have 1024 × 1024 physical or so-called native-format pixels. Note also the effects of the monthly offsetting which applies to all MAMA modes (see Section 7.6). Data taken prior to Mahave the slit center offset above the detector center. Said another way, slit center will project ~3 arcseconds below the detector center along AXIS2 for G140L and G140M observations. Thus there will be ~3 arcseconds less spatial sky coverage to decreasing AXIS2 and ~3 arcseconds more spatial sky coverage to increasing AXIS2 along the slit.
![active sky next or as16 active sky next or as16](http://simlab.wp-x.jp/wp-content/uploads/2016/07/asca-05.jpg)
Note that for FUV-MAMA G140L and G140M the target is placed near AXIS2=392 to ensure that it will not fall on the shadow of the repeller wire (see Section 7.6). PRISM images have dispersion along AXIS1. Figure 11.3 and Figure 11.4 illustrate the format and coordinate system for MAMA images, showing how first-order and echelle ACCUM mode spectrograms appear. Dispersion runs along AXIS1 and the spatial dimension of the slit runs along AXIS2. ACCUM is the mode of choice for all observations that do not require time resolution on minute or less scales. At the end of the exposure, the data can be left in the over-sampled (or highres) format, which is the default for scientific exposures, or they can be binned along AXIS1 and AXIS2 to produce a 1024 × 1024 native-format image. In MAMA ACCUM mode exposures, photons are accumulated into a 2048 × 2048, 16-bit-per-element oversampled array in the STIS data buffer memory as they are received.
![active sky next or as16 active sky next or as16](https://i.ytimg.com/vi/z4OlP68bQZk/maxresdefault.jpg)
The parallel overscan can also be used in the diagnosis of charge-transfer problems.
#ACTIVE SKY NEXT OR AS16 SERIAL#
The trailing serial overscan as well as the parallel overscan pixels are used to determine the bias level in post-observation data processing.
![active sky next or as16 active sky next or as16](http://www.pcaviator.com.au/store/images/D/asky201-01.png)
It includes 19 columns of leading and 19 columns of trailing physical overscan in AXIS1, and 20 trailing rows of virtual overscan in AXIS2. For the default amplifier D, the readout is at the upper right corner. The readout directions depend on the amplifier used. Arrows indicate the orientation of the parallel and serial clocking. Figure 11.1 illustrates the full CCD format and its orientation with respect to the spacecraft (U2 and U3 or V2 and V3) axes. The dispersion axis runs along AXIS1 (image X or along a row of the CCD), and the spatial dimension of the slit runs along AXIS2 (image Y or along a column of the CCD). Scientific data are obtained on 1024 × 1024 pixels, each projecting to ~0.05 × 0.05 arcsecond on the sky. A full detector readout is actually 1062 × 1044 pixels with physical and virtual overscans.