12/22/2023 0 Comments Timetag errors![]() Since this CMOS battery is used to keep your system clock running when your system is turned off, you will get this error on every startup of your computer. This error usually means that your CMOS battery is dead and has no charge left. This error is almost always caused by a problematic CMOS battery. You will usually get an error message saying “your time is behind” or something related to time when accessing internet or some specific websites. The wrong time will also prevent you from using the internet and various websites like Gmail etc. Every time you log in to Windows, you will notice that your time is wrong and it will randomly change on every log in. Even if you follow the instructions, go into the BIOS and change the time settings, it will still change the time back to something else either when you enter into the Windows or when you turn on your computer again. This error will also prevent you from accessing Windows and presents itself only when you power on your computer. This error comes with a few variations, for example, you might see an error code “0271” or a message saying press F1 to enter BIOS setup etc. To protect the MAMA detectors, they are only used for 5 consecutive SAA-free orbits each day.Sometimes, when you turn on your computer, you might hear a beep (or multiple beeps after an interval) and see an error message saying something like “Real Time Clock Error – Check Date and Time setting”. Opto-isolaters in MAMA electronics are susceptible to spurious control signals generated by cosmic rays.Closed loop control of CCD temperature is not possible with Side 2. Short circuit in "Side 1" electronics on 2001-May-16 forced a switch to the backup "Side 2" electronics.Parallel ghost spectra (railroad tracks) are extremely rare, occuring for unknown reasons when observing bright red targets.Out of focus annular ghosts are offset from the main image and contain about 1% of the signal. Image ghosts are caused by reflection off the CCD surface and then the CCD window.Order sorting filters used with first order gratings also give rise to fringing visible in monochromatic images and spatial profiles.A 2-D background subtraction algorithm reduces fractional errors to at most 1%. Echelle scattering is severe in the FUV, making interorder light a poor estimate of background under adjacent orders.On 2001-Sep-13, HST archive software was updated to fix all known TIMETAG problems on-the-fly, even for old datasets. TIMETAG errors in raw STIS data used to cause spurious gaps, negative steps, or large positive jumps in time. Phosphorescence of impurities in the NUV-MAMA faceplace creates a temperature dependent background. Interference noise produces a ripple pattern with a maximum amplitude of 1 ADU in the CCDGAIN=4 setting.Extreme UV over-illumination elevates CCD dark current for times up to 40 minutes.Amplifier Ringing is visible in serial overscan pixels and leads to a small bias depression proportional to the signal in each row.CTI increases by ~15% per year. CTI mitigation is achieved with pseudo-apertures, which place targets closer to the readout amplifier. Measured CTI is worse for weak sources, low background, and time since launch. Charge transfer efficiency (CTE) may be recast as charge transfer inefficiency (CTI = 1 - CTE), which is the fractional loss of charge per transfer to an adjacent pixel.Peak-to-peak fringe amplitude can be up to 30% of the mean in raw data, dropping to less than 3% after calibration with contemporaneous flats. CCD Fringing occurs at wavelengths longer than 7000 Å with both the G750L and G750M gratings.For detail on any of the following items, see the Instrument Handbook. Here we document known anomalous behavior and underlying causes.
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