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Richard: thank you for revealing the term “capsule aperture” to me. I may well contact Russ and suggest that he consider adding them to APT. He has been very welcoming of suggestions for enhancement in the past.
For only slightly trailed images (major/minor axis < 2, say) an elliptical aperture works very well – as measured by comparing the results for untrailed subs and circular apertures with their trailed counterparts of the same field and a carefully chosen elliptical aperture. If you examine some of my entries in the VSS database you will find some examples of elliptical aperture photometry.
Richard: thanks for revealing the term “capsule aperture” to me. I may well contact Russ and suggest that he consider adding them to APT.
For only slightly trailed images (major/minor axis < 2, say) an elliptical aperture works very well – as measured by comparing the results for untrailed subs and circular apertures with their trailed counterparts of the same field and a carefully chosen elliptical aperture. If you examine some of my entries in the VSS database you will find some examples of elliptical aperture photometry.
I can’t comment on ASTAP but can say that APT (A Photometry Tool by Russ Laher) considers circular apertures to be a special case of arbitrary elliptical apertures. This may be an appropriate way of enhancing ASTAP if the code is going to be uprated anyway…
Elliptical apertures are extremely useful for phometry of galaxies. Might they also be for cometary comae?
Thanks for the link to sourceforge. I will check out its contents.
To be a little more serious this time. I may be able to help to some extent, though not with Peranso (my “a frayed knot” comment) because I picked up a very low amplitude EA variable in my analysis of MAXI J1870+070 data. On that occasion I was lucky because an entire primary eclipse occurred in a single night’s data. Subsequent analysis of a few weeks data, not with Peranso, dug out the secondary minimum. The depths are about 25 and 10mmag respectively, well within the range of an exoplanetary transit. Until the secondary showed up I did wonder whether an exoplanet had been found.
All this took place almost five years ago and I will need to refresh my memory before more detail can be given. One of the projects still waiting for another delivery of round tuits is to see what else can be found in this data set and a few others waiting in storage.
Certainly sounds interesting to me!
I would love something that size and have somewhere to put it. I also have no idea how much it would cost to convert it into usable telescope – preferably a Cassegrain-style to keep the size of the housing to a sensible size.
If the BAA as an organization would like to have a robotic telescope in La Palma, please get in touch. I can provide site, power, internet, ancillary equipment like computers, etc at zero cost. Would a subscription model make sense? A significant contribution to construction costs would give you a guaranteed number of hours per annum for the remainder of your BAA membership.
Over the last few years I have been imaging asteroids named for people I follow Twitter and then tweeting the results.
I encourage others to join me in imaging asteroids named after (ex-)BAA members who have been likewise honoured. Over time we should be able to complete a comprehensive gallery.
If anyone is at least remotely interested I could add the ones already taken to my personal gallery.
Richard, I would love to send you a private email so cut and pasted your address directly from the back page of the latest Journal so as to avoid transcription errors. Unfortunately the mail bounced with a “Address not found” and “Your message wasn’t delivered to xxxxxxxxxx because the address couldn’t be found or is unable to receive email.” where I have made the obvious redaction.
Caveat lector!
Richard’s address has been hyp-henated [sic] in the journal and so rendered invalid. Perhaps future editors may wish to check such things before publication.
Richard, I would love to send you a private email so cut and pasted your address directly from the back page of the latest Journal so as to avoid transcription errors. Unfortunately the mail bounced with a “Address not found” and “Your message wasn’t delivered to xxxxxxxxxx because the address couldn’t be found or is unable to receive email.” where I have made the obvious redaction.
Good question, to which I do not have an answer but do have a suggestion: suck it and see.
Take images of a field rich in stars with accurately measured BVR magnitudes (a Landolt field would be ideal, otherwise find a VS at the AAVSO) and see whether your R-band measurements show a systematic dependency on the tabulated B-V and V-R values. If you have Johnson B and/or V filters, so much the better.
Regular flats should take out spatial variation.
Ah, just spotted a very unfortunate tyop! It should have read 1948. I certainly have all the ones from the 1980’s Sorry about that.
I am also interested in the MNRS issues and will be in contact in a couple of weeks.Cheers,
PaulI would like the very early ones please. My collection starts (I think) in 198 and is complete to 2022.
The collection is also 4000km from here so I can’t check for sure until I return to the UK in two weeks time.
I remember a similar Y2K bug in a clock display. The coder appended the year to “19”, rather than adding to 1900. On 2000-01-01 the display read 1 Jan 19100.
Takeaway message: character strings are not numbers, even when they look like them.
It is not just a matter of storage. For instance, some years ago one of my Perl scripts contained this
my ($star, $jd, $mag); while (<INPUT>) { if (/^Variable\s+(.*)/) { $star = $1 and next; } elsif (/^(245\d+\.\d+)\tV\t(.*?)\t/) { ($jd, $mag) = ($1, $2); $mag =~ s/\[/</ or $mag = sprintf “%.2f”, $mag; my ($year, $month, $day) = jd2gregorian ($jd + 0.5); printf “%s\t%.3f\t%s\tLEY\n”, $star, $day, $mag; } }Spot the bug.
Nice to know. I started by doing the best I could with the Spanish (I am trying to become fluent in the language) and then switched to Google translate to complete the task.
My phrase was “barely runs”. I did manage to get it to run eventually, but it seems to be much less stable and reliable for me than is reported by those who run it natively. You may have more success.
Paul
In my experience, it is much easier to convert a DSLR image to FITS than it is to persuade Astrometrica to pay any attention to an embedded WCS.
For JPG and PNG files, nova.astrometry.net will convert to FITS and plate-solve for free. There are any number of free apps to convert from RAW format to something more amenable, including FITS. A very quick search on “RAW to FITS converter” dug up several on the first page.
The major problem with Astrometrica, in my experience, is that it runs natively only under Windoze and barely runs under WINE. I don’t trust the photometry very much either. If the source code were available we could check and perhaps enhance, but it isn’t and we can’t.
Other than that, parts of it are excellent and it is likely what I would use, had I not written a script to track on an object moving from frame to frame.
This raises a general point: should we have a playpen sub-forum where would-be posters can check and edit their proposed postings before subsequently copying the final product to its intended place? This facility is quite common on sites which encourage user-generated content.
Such a place would carry a guarantee that nothing placed there would be permanent (admins or a script could periodically flush everything over a certain age, for instance). It would allow people to learn and it would confine (most) uncovered bugs to a harmless place of quarantine.
