Tonight, it was predicted to be a good observing night. In reality, it was a bit hazy in Bowie, but I still sketched M15 (that’s #27 out of 50 for my Binocular Messier Certificate I am trying for). It is a globular cluster about 33,600 light years away, 175 light years in diameter, visual magnitued 6.2. It is believed to be the densest of all globular clusters in the Milky Way galaxy.

Here is my log (so far) for the Binocular Messier certificate.

The top portion just links to the old site and the observations there.

At the bottom, I put links to the new system. This should be easier to maintain–so i it is no problem to have the same observation under multiple categories (open cluster, Messier object, and binocular observation for example) and with multiple ways of sorting them. Even a keyword search is possible (and in the future).

So, over in the sidebar, click Observations to check it out!

Here is a “beta” of my Observation Report system.

In addition, you can use these links:

www.astrosketches.info/obslog.php?orderby=Date,Start&List=Messier

will (when I am done) show all my Messier object observations (currently, two of them are under this list).

www.astrosketches.info/obslog.php?orderby=Date,Start&ObjectType=DoubleStar

will show all double star observations. There are similar searches that can be done:

www.astrosketches.info/obslog.php?orderby=Date,Start&Constellation=Lyra

for all the objects found in Lyra,

www.astrosketches.info/obslog.php?orderby=Date,Start&InstrumentType=Telescope

< for everything observed with a telescope, and so on.

Use % for wildcard:

www.astrosketches.info/obslog.php?orderby=Date,Start&Object=M%

will get objects whose names begin with capital M (it IS case sensitive!). This would include Messier objects and Mel 111, for example.

go to www.openoffice.org to download the free/open source office software. It can read and write Microsoft Office files (though some rarely-used features don’t translate well–for example, this observation form uses features specific to OpenOffice Writer and won’t look very good in Microsoft Word). Attached is the observation form I currently use for my own observations. The form contains instructions, which I duplicate here for convenience.

Here is the observation form.

Instructions for using Observation Form

Much of this document is protected and one cannot simply type in the boxes having gray areas without getting an error message. Instead, one clicks on the gray, usually, to select from a menu. In general, you can type in the white areas. There are minor exceptions to these principles.

The name field is set automatically. If OpenOffice.org (for Windows XP) fails to set this, find the document file where you saved it and right-click on it and select “Properties”. Click the second “Summary” tab. If there is a “Simple >>” button, press it. If there is an “Advanced >>” button, you are in the right place. Fo;; your name in the third field down, the “Author” field. It is from there that OpenOffice.org fills in the Name field. I put whitespace under the name field to add additional information. Note—if this doesn’t work for you, see below on how to unprotect a field and change it.

The “Date” field is currently unprotected so you can double click it. Make sure the Type is “date”, the Select is “Date” and the Format is whatever you prefer. Then, use the “Offset in Days” field to specify when you made/will make this observation. For example, if it was yesterday, put -1 in. Tomorrow, put +1 in, and so on. 0 means “Today”. Click “OK” when done. If you accidentally delete the date field, CTRL-Z is the undo function. Alternatively, you can put it back in with Insert (top of page menu) then Fields then Date (while the cursor is in the right field).

The Time field is free-form. I personally type things in military local time, such as “22:35—22:47EDT” if I began sketching at 10:35pm and ended at 10:47pm.

For seeing, just click the gray box and select the appropriate value from the list. For transparency, it is the same—click the gray box and select the appropriate value.

For Site, I have it preprogrammed with Alpha Ridge and two other sites I’ve used. See below on how to unprotect a field to change it. Otherwise, just click on it and select the appropriate value.

For Object, click the gray box and type a short name in the popup presented. You probably want to be careful not to hit carriage return, or that will become part of the name! What you put here automatically becomes a label for the drawing. Then, in the whitespace below it, you can type an alternate name or short description.

For Constellation, click the gray box and select from the alphabetical list that pops up.

For Instrument, again, I have my own here, you will probably want to see below on how to unprotect and change a field to replace these with your own instruments.

For Power, click the gray box and select the appropriate magnification. Again, you may want to add or change some of these—see below on how to unprotect and change a field. Optionally, right-click on the picture, then select Picture to get a popup with lots of options to change. For some reason, the “Original Size” button in this popup is broken in my version of OpenOffice.org.

For Description, it is a free-form box. Type whatever you want. Note that there are lines in the background so that you have the option of printing out the form and penciling in the description.

The sketch area is made for drawing on with a pencil (on the printout). But, you can also use OpenOffice.org’s drawing features on it, or even put an image there. To put an image there, click the field-of-view bulls-eye and hit the “Delete” key to remove it. Make sure the cursor is in that box, then select from the top menu Insert then Picture, then either Scan or From File as appropriate and get the picture. It will probably appear in a funny location. Right-click the picture, then select Anchor, then To Page. Then click on it to select it, and you can then move/resize it to put it where you want.

Unprotecting and changing fields

Most fields are protected to prevent accidental changes. However, sometimes one does want to change a field. For example, suppose you want to add your own sites to the menu. Find the Site field, and click in the box to the right, the one with the gray box that might contain text. Right-click this box to get a drop-down menu. Select Cell, then Unprotect. The cell can now be modified.

Next, click on the gray box/text as if you were going to select a new menu item. A popup with the menu appears. Click Edit at the bottom right of this popup. You now can scroll through a list of choices. Highlight a choice and click Remove to delete it, or Move Up or Move Down to change the order. Or, to add a new item, click in the box at the top marked “Item” and type a new item, then click “Add”. Click “OK” when done.

Now, you will probably want to protect the cell again, to prevent future accidental changes. Right click in the cell, select “Cell” from the drop-down menu, then select “Protect.” Finally, don’t forget to save your work (CTRL-S will save).

This general technique can be applied for changing any of the menus: Site, Object, Constellation, Instrument, and Power. You can also unprotect other cells, such as the Name field, then delete the gray box completely with Backspace or Delete, and then fill the cell with whatever you want. Use Insert (top menu), then Fields then Other to get a popup listing every possible fields (including the Input List and Date and Author fields already used here). When done, reprotect the cell to prevent accidental changes.

The trick for typing a name for the object and having it appear elsewhere too is more complicated. You just put fields in both the input and output locations. The input location (which must be done first if I remember right) is an Input Field—and you type a name for the variable in the field marked “Reference”. Then, the output location is a Variable field, and you use the same name for the variable. Finally, don’t forget to re-protect the cell.

As you can see, I think I’ve fixed the problem with commenting.

Currently you have to register to comment…send mail to blog@astrosketches.com if registering doesn’t work.

I have more observations to post–I’m a bit behind here.

The old page (not updated for a time) is still there: http://mysite.verizon.net/vze33d9w/astronomy/

I’ve transferred all the posts over, but not yet the images, links, files, etc. Also, there seems something funny with the dates–old blog assuming EDT and new blog assuming UTC and translating it to EDT, thus making all times four hours off….oh well!

I am quickly using up the space that came with my Verizon website account, so I am working (kind of slowly!) on moving the blog. This is not done yet, but you can see it at blog.astrosketches.info. You could consider it an “Alpha” test. Some posts from here have been moved over (mainly to test how that works), and I’ve made some of the desired color/style changes (e.g. forcing links to be underlined so you can see the links). There is much more to go, and there are plenty of bugs too. You can actually test-comment (only if you register and login first!). No guarantees that your login will stay intact, or your comments, until I officially make the site live, though.

Last night, I posted a method for converting between linear FOV and angular FOV. I have since simplified the procedure greatly. Here is the bottom line:

Let L represent linear FOV, that is, number of feet per 1000 yards (L=305 for my 9×63 binoculars).

Let A represent angular FOV in degrees (A=5.8 for my 9×63 binoculars).

Then:

A = 0.0191 × L

and

L = 52.4 × A

(I hope the “×” symbol works on all browsers–it is supposed to be the “x”, the multiplication symbol).

Ok–for those interested, here is how to “derive” those formulas (which are approximations, but good ones).

Recall that, assuming you have an arctan() function that takes a ratio and returns an angle in radians, the following formula gives you the angular FOV exactly:

A = 2*arctan((L/2)/3000)*180/pi

where pi is 3.1415926535….

The Taylor Series for arctan is:

arctan(x) = x – x^3/3 + x^5/5 – x^7/7 + x^9/9 – ….

Note that because x is very small (typically less than 0.1), x^3/3 (and the higher-order terms) are nearly zero. Thus, arctan(x) is approximately equal to x radians in this situation.

So, the formula becomes:

A = 2*((L/2)/3000)*180/3.1415926535

which simplifies to approximately 0.0191*L.

Now, to get the formula for L given A, just take the reciprocal of 0.0191 to get approximately 52.4.

So, we now see that Freshman Calculus was useful after all!