coatesg

Well, part of it is governed by Poisson statistics and the inherent shot noise arising from the star's signal and the background, and thermal + read noise contributions. I think the plot above is considering the first two largely. The BAA spreadsheet also takes into account the error in reference star magnitudes as I understand it. Error bars of the order of about 20 mmag are about the best I get too. To get better, expose for longer (avoiding saturation), go somewhere darker (though may not make a huge difference for bright objects) or stack images (which is not ideal for some time resolved work).

Looking good - the SXPhe and HADS type stars are all good targets on this type of timeframe - it's satisfying to get a useful result over such a short timeframe. Some are also a fair few mags brighter than +14. Worth also checking out nova/dwarf nova and looking at accretion disc rotation periods (often of order ~0.1d). Often best at outburst.

I found this in our loft when getting the Xmas decorations down - I'd been stung twice by queens in November, and dispatched another 16 in the house - couldn't figure where they were coming from until this point and didn't know it was there in the summer at all. Poor santa.. A 3 foot wasp nest makes for a good show and tell for the kids at school though!

Oof! I just have issues with wax moth around my frame storage - luckily not this! Been a good year for my bees so far, had 17lbs of early spring honey off one hive (which has set quickly as rape seed in there), they have 2 mostly full supers now as well, and have had to do anti-swarm procedures twice already... Also caught a swarm (not mine!) last weekend, so rapidly running out of boxes, frames, space etc...!

That's definitely Vespa crabro, the European Hornet (our native one) - the head markings and yellow down the abdomen give it away. They are enormous, impressive beasts! (The invasive Asian one is smaller, much darker on the abdomen, and has yellow lower legs).

Credit card works really well - use it like a knife to quickly go across the skin surface to get the barb out without squeezing it all in!

A while back I'd chatted to @Helen about trying to schedule some items for the Faulkes/LCOG telescopes to use up some allowance. IY UMa has been reported as in superoutburst (and cloudy here...), so decided to schedule up a time resolved series to look for superhumps - the request didn't go on for quite as long as I would have liked (it did 72 out of 120 90sec exposures), but I still seemed to grab a nice curve - a longer run would give the two peaks and hence the orbital period, but unfortunately, the request stopped and didn't complete (probably scheduling - maybe there's a way of getting all the observations in one block?) Here's the output graph (with two comp stars plotted (Magnitudes in V band - was taken with an SBIG 6303 on one of the 0.4m SCT from Teide, Tenerife - https://lco.global/observatory/0.4m/)

Don't know if you have already, but if you have the Time of Minimum for primary and secondary, you can submit for inclusion in the JAAVSO - there's details on the AAVSO Eclipsing Binary page. Cheers

Nice observation (And yes - this is an object with requested observations as it goes towards a predicted increase in brightness when the smaller black hole passes through the theorized accretion disc of the second - I had a go at magnitude measurement a few weeks back but got clouded out...). is correct for the naming source, but it was named as such because Blazars encompass both BL Lac objects and OVV (Optically Violent Variable) quasars as sub types. (The distinction being the BL Lacs are related to radio weak galaxies, whereas OVVs relate to radio loud galaxies). In reality, Blazars are a sub-type of the larger quasar group ("Quasi-Stellar Object" - appears point like like a star, but the spectra/variability is non-stellar), where the relativistic emission jets of the feeding black hole point along the line of sight for blazars - BL Lac and Blazar are often used interchangeably, but that's not quite the whole story ?

Very nice! (Presume this is the same data repeated to give 2 periods on the phase diagram - esp given a 6hr period?).

Think this looks like a great start - if you can get the two panes to match, it's going to be a great result!

I have just detected it before in 6.5hrs of exposure using a modded 350d and a 85mm lens at ISO400, f4 : https://www.chromosphere.co.uk/2017/12/18/widefield-flaming-star-and-spaghetti-nebulae/ A cooled cam with better response would improve things, but it's very faint and I'd expect days of exposure would be needed to get anything approaching the contrast above...!

Another HADS star from last night, V467 Dra - this one has a period of 4.74hrs, so I let the scope chug away. Guiding was working really well as well. This is from 369 separate 30sec exposures over almost 5hrs, through 350mm f4.6 newt, V filter, ST2000XM. Transparency not so great and the y-axis is quite expanded compared to some other HADS plots as there's only 0.35 mags variation for this one.

Yes. The Northumberland at Cambridge is very much in use (12" something like f20...) - the University AS and CAA use it. When I studied there I used it a bit, but always preferred the rather good 8" f14 Cooke refractor (The Thorrowgood) next door... (Had a feeling the 28" at Greenwich is still used though)

Well, the biggest might have been the INT, before that departed to La Palma. The 36" at Cambridge (https://www.ast.cam.ac.uk/about/36-inch.telescope) is optical, and still in use for research on double stars IIRC - Edinburgh looks also to have a 0.9m Cassegrain (36") but (according to the wikipedia page) is no longer in use. (?) The 36" Yapp at Herstmonceaux also ties I think, but the 38" Congo at Herstmonceaux beats them all (though don't believe it is in use, and never had been, as the optics were rubbish...) I would guess Lord Ross' Levaithan at Parsonstown is probably the largest in the British Isles (but not the UK as it's in the Republic of Ireland) - 72"/1.8m!

If I've been short of comparison stars, for a quick analysis I've looked at using the stars in the AAVSO APASS catalogue (you can access the data really easily by using Simbad). When I've requested an "official" sequence via the AAVSO process, they've used the same data. Though, I did manage to request a set of comparison stars recently, where there was nothing usable above 14th magnitude in the FOV (I had a shade under 30' like Dave) - the errors in the brighter comparison stars were up to 20% of the range of the variable itself ? - exception made to use them as the data can be adjusted later if the comparison stars are improved by a subsequent survey. (It makes no difference for timing studies, but for getting absolute magnitudes it does somewhat!).

Depends a little bit on how good your guiding is I think - do you have any details on the ability of the HEQ5 to guide successfully? I say this, as it gets increasingly hard to guide at longer focal length, though a catadioptric is probably easier than a longer tube scope like a newt (less moment of inertia). If the mount is up to it, then a Newtonian would be possibly the cheapest way forward I think in terms of price vs aperture - you will need to learn to collimate though (it's not too hard once you've done it a few times - it takes me longer to take out the camera, and reconnect it afterwards than the actual collimation these days). Having a perm setup also helps enormously.

(Odd it came out as a double line though - suspect possibly a debayering artifact?)

Assuming the image was captured sometime over 2300hrs on 2018-01-01, there's only two possibles that an MPC search (https://minorplanetcenter.net/cgi-bin/checkmp.cgi) around 6 arcmin comes up with - 2013 YD60 (426964), or Luisa (599). The former is mag 21.something, the latter mag 12.something so with that, and manually looking at the ephemeris and moving a mouse around to see where the RA/Dec is, my guess is that it is Luisa. A single sub with date/location would pin it down exactly.

Lovely image - it's very natural and has a real 3D effect to it. LBN785/Ced31 (to the left) looks like an interesting target for a close-up too.

Ditto on slowness. Not on laptop so can't see if it's connectivity, ttfb or resource blocking that's the issue though. Will check it out tomorrow if still slow.

Thanks for the kind words all I really do like imaging with this combo.

I grabbed 3h40m of the Sadr region stretching from the crescent up to NGC6914 (not visible as it's a reflection neb!), in HA light - may add to this in HA, but also would be nice to bring LRGB into it at a later date. QHY163M, Canon 200mm 2.8L II (working at f3.85), Losmandy GM8 - taken 17th Sept 2018, West Oxfordshire. All in 5min subs, guided with a ASI120MM on a 50mm guider. Baader 7nm filter. Processed in PI. Thanks for looking. (ergh - jpg compression artifacts aren't great in this

Looks good - Just wonder if there is more there to be pulled out - perhaps leaving the background lighter would help to show the fainter reaches? Also, maybe masking the core while processing would stop the details near to the centre blowing out a bit.

Always errors - even Messier had a couple of errors... Catalogues will also always vary in values (eg comparing Sh2 to NGC/IC will always give slightly different values for the same object) - the VizieR catalogues are (should be!) straight copies of catalogues from papers and they have the publication reference in the search results. You'll also find that a lot of deep amateur images show a lot more than professional catalogues indicate. Remember as well, if the paper is reasonably old, the original coords will be in J1950, so that's why you need the J2000 coords to account for precession.