Re: (IAAC) Double Star Observation
> (The methods I use are described in the double star section of
> my site, given below). However I think I am now in a position to start
> actual measurement using a micrometer, which is where I need help.
Nice site, Paul! And thanks for your introductory post!
Are you familiar with the Webb Society? They are an international deep-sky
observers' organization, with a historical base in England but membership
worldwide, I mention them for 3 reasons:
(1) The Webb Society is an excellent resource for ALL deep-sky
observers to know about, no matter their interests;
(2) There is an entire Section of the Society devoted to double
star observing techniques, tools, and recording methods; and
(3) They publish a handbook (Vol. 1? in their Handbook series)
which covers double-stars in quite considerable detail, as
well as Quarterly reports of members' double observations.
For more information on all of this, peruse their Web site! It's at:
> I understand that there are certain other sorts of micrometer
I occasionally use a simple, handmade micrometer for my 20", Paul. It will
definitely NOT approach a decent filar micrometer in accuracy, nor can it be
used for any but the brightest doubles within range of my scope. But it took
very little time to make! The design is called an "interference micrometer":
it's basically an aperture mask over the front of my scope, composed of a
series of regular slats. These slats cause an interference pattern from
starlight, whose orientation can be calibrated and used to estimate both PA and
separation. This design is covered in the Webb Double Star handbook.
I've also been interested for a while in another design mentioned in the
handbook: it involves a laser light source (like that used for laser
collimators, or simple laser pointers). The beam is split by a group of lenses
and prisms, and aimed up the tube at your secondary. The separation and
orientation of the split beams can be manipulated precisely, to estimate PA and
separation. And with a little electronics wizardry, the brightness can also be
adjusted, both to observe fainter objects, and to estimate magnitudes. The
design in the Webb book actually uses flat mirrors to direct the beam into the
light path, but for larger-aperture scopes, the whole laser plus prisms might
fit right in the shadow of the secondary!
> I am keen to start to post observations on netastrocatalog, and I
> shall post the visual estimations made by the BAA Student Group
> over the past 3 years (a project I co-ordinated) very soon.
And we're keen to have them1! Also, if anyone else from BAA SG may be
interested in the 'catalog, be sure to tell them about us... ;>
> PS. Please CC: directly... as I am not yet fully on the list.
You should now! Please RSVP me personally when you get this, Paul.