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uncertainty of CMOS vs CCD observations

Federico Spada All Messages By This Member #33106 Hi all, ? I am currently working on fitting the orbits of some long-period comets based on data obtained from the MPC database. In assigning uncertainties to the data, my orbit fitting program follows the weighting scheme proposed by Veres et al. 2017, Icarus, 296, 139, which depends on their type, observing station, reference catalog, and, sometimes, their specific observing program. For CCD observations, these authors recommend a conservative 1.0 or 1.5 arc seconds uncertainty, depending on whether the reference catalog is known. This weighting scheme, however, does not address observations obtained with CMOS detectors (MPC observation type code "B", as opposed to, e.g., "C" for CCD observations). Does anybody have any recommendations on how to assign the uncertainty to CMOS observations? ? Best wishes, Federico
Luca Buzzi All Messages By This Member #33107 I personally don't imagine why CMOS observations must have a different weighting respect to CCD observations. Luca #204? toggle quoted message Show quoted text Il lun 23 dic 2024, 10:00 Federico Spada via <federico.spada=[email protected]> ha scritto: Hi all, ? I am currently working on fitting the orbits of some long-period comets based on data obtained from the MPC database. In assigning uncertainties to the data, my orbit fitting program follows the weighting scheme proposed by Veres et al. 2017, Icarus, 296, 139, which depends on their type, observing station, reference catalog, and, sometimes, their specific observing program. For CCD observations, these authors recommend a conservative 1.0 or 1.5 arc seconds uncertainty, depending on whether the reference catalog is known. This weighting scheme, however, does not address observations obtained with CMOS detectors (MPC observation type code "B", as opposed to, e.g., "C" for CCD observations). Does anybody have any recommendations on how to assign the uncertainty to CMOS observations? ? Best wishes, Federico
Roberto All Messages By This Member #33108 There should be no astrometric differences between the two types of sensors. I have used both the CCD until a couple of years ago and now a CMOS sensor and I do not see any differences due to the type of sensor. From a photometric point of view we can talk about it but even there there should be no differences (if the system is calibrated well). Regards, Roberto Haver 157 Frasso sabino On Mon, 23 Dec 2024 00:52:16 -0800 "Federico Spada via groups.io" <federico.spada@...> wrote: Hi all, I am currently working on fitting the orbits of some long-period comets based on data obtained from the MPC database. In assigning uncertainties to the data, my orbit fitting program follows the weighting scheme proposed by Veres et al. 2017, Icarus, 296, 139, which depends on their type, observing station, reference catalog, and, sometimes, their specific observing program. For CCD observations, these authors recommend a conservative 1.0 or 1.5 arc seconds uncertainty, depending on whether the reference catalog is known. This weighting scheme, however, does not address observations obtained with CMOS detectors (MPC observation type code "B", as opposed to, e.g., "C" for CCD observations). Does anybody have any recommendations on how to assign the uncertainty to CMOS observations? Best wishes, Federico
Gary Bernstein All Messages By This Member #33110 Either type of detector should be capable of measuring positions to a few tenths of a pixel (which will be well below 1" in most cases) with basic centroiding and a good solution to a good reference catalog.? Of course that depends on how much time the measurer devoted to the task, but CCD vs CMOS makes no difference at this level.? We achieved accuracy down to 1-2% of a pixel on the Dark Energy Camera, and this has been done by other CCD survey cameras, but I don't know if that has been achieved yet with CMOS devices.?
Dan Green All Messages By This Member #33111 CMOS vs. CCD shouldn't matter, nor should "estimated" uncertainty of individual astrometric positions. What should matter is leaving out observations with bad residuals -- something that the MPC doesn't do much -- and not publishing perturbed orbits for comets with short arcs.? The MPC should only be publishing parabolic orbits for new comets that have highly elliptical orbits -- and certainly not hyperbolic solutions with 1- or 2-week arcs.
Federico Spada All Messages By This Member #33121 Thank you all for your replies! This is more or less what I expected, but now I feel more confident after having independent confirmation from people with direct experience on the topic. Happy holidays! Federico

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