andrew s

Not having a 1 m class telescope at a first class location for my personal use. (Which goes to show how lucky I am to have the rig I do in Castillejar) Regards Andrew

If they drift left or right then that is due to the doppler shift as they move away or towards you. Regards Andrew

Pay back for all the light they captured. Has to be returned some day. Even black holes do in the end (according to Hawking) . Regards Andrew

Two flares in one night ! All the more amazing as the weather has not been that good in Spain. Will make a good pair to analyse. Regards Andrew

@robin_astro the H alpha is back. No astrophysical marvel just a software error. take me back to computer validation days in the Pharmaceuticals industry! Regards Andrew

Impressive hand control. Regards Andrew

Impressive, how do you attach the camera ? Regards Andrew

@George Jones please give us an update on the talk and your take on it. Interested to here the speakers view on why the LHC has not found any evidence for particles beyond the standard model . Other than the standard " they are beyond its energy range". Regards Andrew

Yes

Thanks Robin, I am trying to research this in the literature. It could be it's too hot? Work to do on this. Regards Andrew

Well almost a year later I have found a reasonably easy and reliable way to process my flare spectra. The attached shows the first and still the strongest flare I observed. After calibrating the images in astroimagej the spectra were extracted in ISIS. They are necessarily noisy so they were wavelet filtered in Python. I also used Python to subtract the pre-flare star spectra leaving a good approximation to the flare light. Here are the results as a contour plot and an animated gif. Regards Andrew

Take darks at the two extreem temperatures and compare them. If the are very close then just use one set of darks. If not you will need to calibrate them with the corresponding temperature darks or scaled darks depending on what your camera is.. Regards Andrew

Very impressive with great contrast and drama. I just love the diffraction spikes a real image. Regards Andrew

Indeed a fine image with to my eye a fine colour balance. Regards Andrew

@michael.h.f.wilkinson I see it cost the shirt of your back. Sepia too! Regards Andrew

Classic gray scale, very retro and none the worse for that. Charming image. Regards Andrew

If Netflix The Crown is to belived one family still does even at breakfast. Regards Andrew

Sorry but my Daguerreotype plates have deteriorated beyond restoration. Regards Andrew

If you want to do photometry I would use the AAVSO or BAA charts. The magnitude in catalogues vary as they were measured under varying conditions at various times. Getting precise magnitudes is very difficult and requires excellent skies. That's why most amateurs do differential photometry which is much easier. Regards Andrew

Now I have subtracted the star so only the flare shows (plus residual noise from the star Regards Andrew

There are 3 levels of equivalence principle: Weak Equivalence Principle (WEP): All uncharged, freely falling test particles follow the same trajectories, once an initial position and velocity have been prescribed. Einstein Equivalence Principle (EEP): The WEP is valid, and furthermore in all freely falling frames one recovers (locally, and up to tidal gravitational forces) the same laws of special relativistic physics, independent of position or velocity. Strong Equivalence Principle (SEP): The WEP is valid for massive gravitating objects as well as test particles, and in all freely falling frames one recovers (locally, and up to tidal gravitational forces) the same special relativistic physics, independent of position or velocity. but yes it needs to explain the equivalence. From the paper linked to above. Stop blaming the hammer it's your foot that is applying a proper acceleration (deceleration ) force to the hammer. Regards Andrew

Just come across this very easy to read popular article on the impact of gravitation waves on alternative theories of gravity Alternatives to GR. Easy read. Regards Andrew

The simple answer is no. The difficulty rivals face is that in direct tests of GR both locally of the scale of mm to astronomical distances it does exquisitely well. This means for rivals that "They can either study minimal deviations away from General Relativity, or must otherwise look for mechanisms that hide modifications to gravity on the scales probed by experiment." This is a tough challenge and tends to leave them trying to do away with Dark Matter and Dark Energy. However, "Of course, if we wish to account for dark energy, or solve the cosmological constant problem using modified gravity, these deviations must be manifest in the solutions of the Friedmann equations. We must also require, however, that they do not spoil the successful predictions of the standard cosmology..." This tends to results in comparing simulations of various cosmological events, galaxy formation or cluster collisions etc and comparing them with what is observed. Such comparisons are rarely definitive. The quotes are from the review paper I linked to before. Since this review gravitational waves were detected with the form predicted by GR and this ruled out a class of rivals. Regards Andrew PS @saac here is the paper again Modified gravity and cosmology . Just scan it and ignore the maths it is interesting and a lot can be got from it by just reading the intelligible bits!

Nice observation. Anyone thinking of trying note you must use a filter. Don't look at the sun directly with the naked eye. Regards Andrew

Normally the RA setting circle need to be adjusted to your local sidereal time at the time of observation. Regards Andrew