observer’s images – plate solving error

[Robin Leadbeater]

I see the plate solving system has managed to “solve” a graphical image of mine from pre the system update

https://britastro.org/observations/observation.php?id=20180609_220000_74db4bc556ca03c8

I tried to use the reporting tool to correct it but I get a “permission declined” error

Cheers

Robin

[Robin Leadbeater]

similarly this one

https://britastro.org/observations/observation.php?id=20201130_172000_14eeb4c49a70db2e

Robin

[Dominic Ford]

Hi Robin,

Thanks for reporting this.

The plate-solving system does produce a significant number of false positives, unfortunately. The reporting system was introduced last weekend as the easiest way to remedy this, and when I notice false positives myself, I often flag them right away. However, there’s clearly some outstanding permissions issue that my testing didn’t pick up.

I won’t be able to look into this until very late tonight, but I’ll aim to get this fixed for you tomorrow.

Thanks,

Dominic

[Dr Paul Leyland]

My offer of assistance from a few months back still stands.

Paul

[Dominic Ford]

Hi Paul,

Many thanks for your offer to help.

To fill everyone in, the plate-solving facility of the new image galleries is certainly somewhat experimental. When it went live in December, there were a few teething problems that we identified. Among these:

* Plate-solving images that cover a very small area of sky can be very slow, and we imposed a time limit of 4 minutes on the software (and on a rather slow computer). In practice, some images can take up to 20 minutes of CPU time.

* We did not correctly solve images with EXIF rotation headers.

* We did not correctly solve colour-inverted images.

* We had a significant number of false positives – for example, photos of grass which supposedly resembled some star cluster.

Within recent weeks, I updated our automated software to fix these issues, and invested 8,000 CPU hours in re-solving the entire archive of 47,800 images – this time with a time limit of 45 minutes for each image, and on a computer twice as fast as the one I used in December.

The result has been a very dramatic increase in the number of images for which we have sky coordinates – specifically, an increase from 11,950 to 23,363. We do still have a significant number of false positives, but in the short term we think the best way to deal with those is to offer a facility to flag them (as Robin refers to). BAA members are able to flag their own images, and a small number of administrators also have the power to do so.

I’m not sure we have any immediate plans for further developments, though we’re always interested to hear feedback. We’ll certainly let you know if we have ideas for ways in which you can help.

You might find the two plots below rather interesting. The first is a histogram of the time taken by astrometry.net to solve the images in the archive. The second is a scatter plot of run-time against the angular width of the image.

Best wishes,

Dominic

PS – I’m about to look into Robin’s original issue now, and will post separately when I have more news.

[Dominic Ford]

Hi Robin,

I think the permissions issue you had is now fixed. You should now be able to flag any of your observations which have been incorrectly plate solved.

I’ve flagged the two images you linked above myself, and also taken the liberty of updating the object tagging on the Nov 2020 image, so that it will come up in any searches for images of those two novae. The two novae weren’t in the object database at the time you uploaded the image, but I added them a few weeks ago.

Thanks again for reporting this,

Dominic

[Robin Leadbeater]

Thanks Dominic,

While I have your ear ;-)…   I embedded some links in the description of the image and selected the “new window” option expecting it to open the link in a separate window but it closed the original window. Is this how it should work ?

Cheers

Robin

[Dominic Ford]

Hi Robin,

Thanks for reporting this. The HTML filter that I use to ensure the descriptions don’t contain nefarious code was apparently blocking the “target” attribute on web links, and so the “new window” option was getting blocked. I can’t see any reason not to allow this.

It should now be working, and you may well find that any links you have previous set to open in a new window will suddenly now start working as intended.

Cheers,

Dominic

[Robin Leadbeater]

The links do indeed now work as intended. (Using “open new window” ensures the reader can visit the links without closing the BAA website tab)

Thanks Dominic!

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