Daniel Perley's Guide to Star Parties


Updated for Fall 2006.

14-Inch Telescope

Setup:

0. Show up about 20-30 minutes early. You need to post signs around the building to direct students to the roof and get through the setup procedures before students begin to trickle in. (Once this becomes more routine you can probably cut it a bit closer, but play it safe for now.)

1. Open the front door to the dome, which requires a common-area key (you will need to get one from Sandy). If the door has problems, try pushing the knob inward before turning the key.

2. Open up the dome slit. To do this, pull the center rope with one hand while pulling the left rope with the other.

3. Remove the lens caps on the telescope and finder scope.

*4. Remove the eyepiece cover (use thumbscrews) and insert an eyepiece. Smaller eyepieces require the fitting ring to fit properly.

*5. Plug in the telescope (connect to the adaptor cord) to where it says "12v DC in"

*6. Plug in the controller to the leftmost port. (NOT the one that says "autoguider".)

(You may be able to skip some or all of 3-6 if things have been left set up by the last user.)

7. Turn the power on with the power switch.

8. The hand-paddle speed defaults to ultra-slow for some reason. Before doing anything else, press "1" (aka SPEED), then "5" to set it to a faster speed.

9. If necessary, make sure the telescope is in the home position: the altitude marks on the side of the telescope should be aligned with zero, as should the azimuth marks on the front. Use the hand-paddle arrows at the top of the controller.

10. The telescope will ask you to choose an align method. (If it does not, press 'Mode' once or twice to go to the main menu, and then scroll to 'Setup' > 'Align'). Scroll with the lower up/down arrows (NOT the handpaddle keys) to 'Two Star' and press Enter. Choose a bright winter/spring star from the list: Sirius, Procyon, Rigel, Betelgeuse, Aldebaran, and Alpheratz are good candidates right now, as are many other bright stars. Press Enter; it should slew to near that star (though the alignment will not be exact).

11. Rotate the dome using the buttons on the north side of the pedestal so you can see the object down the barrel of the telescope and in the finder.

12. Center the star in the eyepiece, using the finder if necessary. (If it is not visible, search around until it appears in the eyepiece; then center.) Now look through the finder and check if it's in the crosshairs, or close to it. If it isn't, move the finder scope around until it's centered there too. (This can be tedious, *will* save you time later, and you may need to repeat this step if a students whacks their head on the eyepiece. Normally it is not necessary.)

13. If necessary, adjust the focus. Keep the telescope pointed on the bright star, and adjust the focus knob until the blur is reduced to as small a point as possible. (If you are using a different eyepiece, this may be a large adjustment; if not, you can probably skip this step entirely.) Don't worry if this causes the image of the star to move around a little bit.

14. Make sure the star is centered in the eyepiece, and press Enter. It will ask for another star; choose another bright candidate.

15. The scope is reliable enough that the second star should be nearly dead-on with only a small adjustment needed. Press Enter when centered.

16. To find an object, you can scroll through the menus (in general, Mode means back and Enter means forward), or also use various numerical shortcuts (such as the M button for Messier objects). Once you find your object in the list, press Enter and *then* Goto to slew. If the alignment is not perfect, you can manually steer a bit with the hand-paddle. (You can then re-align using the new object by pressing and holding Enter to improve future pointings if you wish.) You'll need to move the dome, and possibly swivel the eyepiece as well for the object to be more easily viewable.

Things to NOT do:

- Don't touch the death knob on the side of the telescope. Fortunately it doesn't exist anymore, but this bears repeating anyway.

- Don't lock the mirror; it's easy to mistake that knob for the focus. Locking the mirror disables the focus knob.

- Don't pilot the telescope over wide angles manually. The auto-tracker works, so use it. (If you really want to scan around an area manually, point to something nearby first.) Very large manual rotations risk hitting the hard-stop and damaging the telescope.

Close-down:

1. Press 'Mode' (several times if necessary) to go to the main menu. Scroll with up and down to Utilities, and then scroll to find Park Scope. Press Enter.

2. The telescope should slew to the home position. (If not, align it due North and level yourself with the markings on the side of the telescope.)

3. Replace the lens caps / dustcovers.

4. Power off.

5. Close the dome. Hold the middle cord while making a quick tug on the right cord; release the middle cord at contact to latch the dome shut.

6. You don't need to replace eyepieces or unplug cords (unless it's going to be a long time before the next star party), but make sure the room is in reasonable shape before heading out.

In case of emergency:

Dan's phone number is 510-316-2879. Jonah Hare's is 510-590-6921.





Eight-Inch Telescope

Setup guide - or, how to avoid going to Plan B in the first place.

0. Show up at least 30 minutes early, if not 45 minutes. Assuming you're not already super-familiar with the telescope (and if you need these instructions presumably you're not) it takes at least that long to get set up and likely much more if there's a technical problem.

1. Open the dome (you have to push the knob inward a bit after you insert the key to get it to unlock) and retrieve the following items:
- Telescope
- Power supply (if it's not broken)
- Eyepiece (with fitting ring if it's not already attached)
- Tripod
- Controller

2. Extend the tripod legs a few inches. Don't overdo it, lots of students are not that tall and it's easier to kneel than balance precariously on a chair. Make sure the tripod is approximately level.

3. Orient the telescope so the control panel faces South and place the telescope down on the center of the tripod, fitting the metal rod into the hole in the bottom of the telescope. (Requires two people.) Screw the metal rod all the way in until it's fairly tight.

4. Release the declination lock and point the telescope so it's level; then fix the declination lock again. Don't touch the RA lock except to check that it's fixed.

5. Remove the eyepiece cover (use thumbscrews) and insert the eyepiece. Requires the fitting ring to fit properly.

6. Remove the lens caps on the telescope and finder scope.

7. Plug in the power supply if you have it. Try to keep it safe, either right underneath the telescope or behind some obstacle, so students don't step on it.

8. Plug in the controller to the leftmost port. (NOT the one that says "autoguider".)

9. Turn the power on with the power switch.

10. Press and hold "5" to skip the annoying Sun warning.

11. Press 'Mode' once or twice to go to the main menu, and then scroll to 'Setup' with the bottom pair of arrow keys (I think, it might be called something else) and choose "two-star" as apparently this is the most reliable method. The telescope will get a GPS fix and ask you to choose the first star - probably go for Vega, Deneb, or Altair, since these are really bright and easy to find for this first one. So select one of those with the bottom pair of arrow keys and press Enter.

12. IMPORTANT - take this opportunity to calibrate the FOCUS and FINDER SCOPE POSITION. The telescope will point near the star you chose, and you have to scroll with the upper arrow keys until you find it. My method for doing this is to park your head a few inches behind the finder scope and keep both eyes open, which will let one eye look through the telescope while another can still see the star directly. When the star appears in the finder scope, move it to the center (crosshairs) and look through the main scope. You probably won't see it, becaues the finder scope gets knocked around and doesn't always point the same direction as the actual telescope - so you will have to search a bit.

13a. If you CAN find the star, go back to the finder scope and move it around with your hand (it pivots slightly about its base; that's the whole problem) until its crosshairs actually point at the star.

13b. If you CANNOT find it after a minute or so... well, you have a bit of a problem. At this point I would suggest pointing (manually, using arrow keys) at the Moon or Campanille or something else huge and bright, then moving the finder scope manually with your hand until its crosshairs point at the same feature you actually see in the real telescope. Then go back to your star (manually) and see if you can find it.]

14. Anyway, once you DO find the star in the main scope - if the star does not already look like a point (and especially if you can see a hole in the middle), adjust the focus knob a bit. This causes the star to actually move in the field of view, which is a bit weird, but eventually you'll get it straight. Make sure the star is in the exact center of the field of view of the telescope.

15. Press Enter. The telescope will ask for another star; you can just use another member of the Summer Triangle if you wish (even though they're close to each other this wasn't a problem last night.) After it finishes slewing, point to it with your now-properly-calibrated finder scope, locate it INSTANTLY in the main scope, center it, and press Enter again.

16. That's it! Now you can use the finder to actually point at things for you, and hopefully it will work. If not... well... that's life. :)

Also, Plan B is still useful even when things go smoothly. It takes two people to set up and take down the telescope, so the 'secondary' may as well hang around in the mean time to do constellations and talk about stars.



Object guide:

Arranged roughly from West to East. The later in the academic year your star party, the later the objects on the list you can see. Most of these are up all semester, however.

Jupiter - Low in the west near sunset. Under good conditions (that will probably not be attained due to its low elevation) you can see its atmospheric bands and the Great Red Spot. Even this semester, though, the four moons should be bright and easy to see. To identify which moon is which, take a look at Check out http://skytonight.com/observing/objects/javascript/3307071.html before heading out to observe.

M13 - Globular cluster in Hercules.

Mizar/Alcor - Quadruple (maybe quintuple) star in the Big Dipper. You can't distinguish the stars in the two close pairs, though, so Mizar just looks like a double, with Alcor also not faraway in the field of view.

Albireo - "Cal star" (almost directly overhead, maybe a bit to the West). This one is very popular with the students, and also quite easy to find (even manually if necessary).

M57 - Ring Nebula (planetary nebula in Lyra in the Western sky) Extremely faint; hard to even be sure you're seeing anything on nights when the moon is out.

M15 - Globular cluster; almost as good as M13 and often better for fall viewing.
Uranus - This is actually up in the evening, as is Neptune. It's not clearly resolved, but the color is noticeable.

M31 - Andromeda Galaxy (visible in Eastern sky/overhead) Fuzzy patch; students won't be too impressed. Moonless nights help.

NGC 869/884 - Double Cluster. There's a nice double open cluster between Perseus and Cassiopea.

M45 - Pleiades, an open cluster; you can see it with the unaided eye very easily in the eastern sky, then see the whole cluster with the finder scope, and zoom in on part of it with the main telescope. This helps give students (and GSIs!) a sense of the amount of magnification the telescope provides... and is also just pretty in general. Students often find this object on their own and will ask you what it is.

M42 - Orion nebula; the Trapezium cluster of O stars in the center is surrounded by a haze of subtly greenish gas emission.

Saturn - Rising in the East. The rings are clearly visible; on good nights, the Cassini division and many of its moons should also be visible. Check out http://skyandtelescope.com/observing/objects/planets/javascript/saturn_moons.html to find its moons.

M82 - Nearby irregular galaxy; more compact (higher surface brightness) than M31.

Beehive cluster - Open cluster in Cancer.

Iota Cancri - A double star (binary) with a hot blue main-sequence star and a yellowish giant star in orbit around each other. (The 'Cal star' of the spring.)

And, depending on the time of the month, the Moon is often up as well.


Finding objects: For Messier objects, once the telescope is booted up and you're on the select object screen, I believe you just press the number that has "M" written above it, then enter using the digits the number of the object you want. It'll display the full name, then you press GoTo a couple times and after an infernally long delay that always makes you think it's broken it'll eventually decide to cooperate and actually point at the object.

For stars, press the number with "Star" written above it, then choose "named", and scroll through a long list of options with the arrow keys to find the one you want; press Enter and it'll give you its scientific designation as well. Then do the same GoTo thing.

(This is from memory; I may have forgotten some steps.)


Also, for those unsure of their way around the night sky I found a website that generates instantaneous star maps for any location / time:

http://www.fourmilab.ch/cgi-bin/uncgi/Yoursky
(Berkeley coordinates)

Berkeley's coordinates are about 38 degrees North, 122 degrees West. During daylight savings time we're 7 hours behind UTC, after the end of DST we're 8 hours behind UTC.




Plan B: In Case of Emergency...

So, what happens when things don't go as planned? Certainly most of the time this semester [Fall 2004], for part/all of the evening some sort of technical difficulty with the telescope, or just an underestimation on how long it would take to get it set up, has lead to long periods where we have 30 students sitting around wondering why they bothered to come out to Campbell in the middle of the night just to wait around for the GSIs on duty to get things fixed. At many such star parties when I was in the vicinity (and not responsible for the telescope), I grabbed a group of bored-looking students, walked up to the roof, and went over stars and constellations. This actually has worked out really well - though as we all know the constellations themselves are pretty irrelevant, it's pretty easy to sneak in lots of cool astronomy facts and even casually bring in some concepts from the course. So, I figured I may as well share the little spiel for this I've developed with the rest of you in case you want/need it for future 'technically-challenged' star parties... until the 14" gets fixed for real.


1. Getting Started

Just go to the biggest group of people there and announce you're going to "do constellations" or something else fairly innocuous. Most people won't care. That's fine, you need only a couple people to 'seed' it and pretty soon you'll have a crowd tagging along to see what's going on. Then head up to the top of the stairs (if you're not there already) and let them look at the pretty view of the city before launching on the grand tour.


2. Grand Tour of the Sky

Probably the best thing to do next is a whirlwind tour of the sky. Best place to start is probably the Big Dipper, which everybody recognizes; proceed to Polaris, then probably Cassiopea, the Summer Triangle (pointing out Cygnus and the Cal star, of course; *everybody* wants to be able to find this one), Bootes, Sagittarius, Scorpius (if you can find it), and Pegasus. And any other constellations you like, though students will have difficulty finding anything other than the Dipper, Cassiopea, and the Summer Triangle, so don't belabor them too much. (These are the fall constellations, of course. In winter and spring obviously this path will have to be modified a bit, as will the whole discussion below.) Obviously this means you have to know the constellations and stars in the first place, of course, but it's not too tough. More on that later.


3. Stars

Once you've finished that, inform them that it's all irrelevant because constellations don't have any physical meaning. Cassiopea is probably the best example, since it's easy to find and we just went over that in lecture. The stars are:
Segin (Epsilon, left point of the 'W') - 440 ly (B class)
Ruchbah (Delta, bottom-left of the W) - 100 ly (A)
Navi (Gamma, center) - 600 ly (B)
Shedar (Alpha, bottom-right) - 230 ly (K)
Caph (Beta, right point) - 54 Ly (F)

So, tell them we can measure the distances (mention 'parallax' after we cover that in lecture, which presumably we will pretty soon?) and that they're extremely different. If you can memorize Caph and Navi's distances that will help drive the point home, and students will hopefully be very impressed if you can rattle off the name and distance of all five. (I'm working on it for next time.) Then ask them how they can be such different distances and yet look about the same brightness to us. They'll have no trouble telling you that one is just much brighter, and you can then impress them by telling them just *how* much brighter (250 times or so - Caph is 28 Lsun and Navi is 70,000 Lsun)

An even bigger contrast is the Summer Triangle - Vega is 25 ly, Altair is 17 ly, and Deneb is... about 2500 ly. Which means that (again, since they look about the same to us) Deneb has to be about 4000 times brighter than Vega, which is already 50 times brighter than the sun. So Deneb is almost a quarter million solar luminosities, one of the brightest stars in the entire galaxy. If it were as close as Vega it would outshine the crescent moon.

So, the students might ask (or more likely you ask for them), how can it possibly be so bright? Well, one thing that you can note is that stars are different temperatures - point out Arcturus's orange color, and remind them of Alberio (Cal star, it helps if the telescope is functioning by this point and some of them have seen it). So some stars are fainter (partially) because they're cooler ("as you might remember from lecture.") (If you want to impress with numbers, Arcturus is 4000 K, the sun is 5800 K, the stars of Alberio are about 20000 and 4000 K.)

But, Vega and Deneb are about the same color, so that can't be it in this case. So what could it be? Somebody will probably speak up and give the right answer, surface area. But, of course, it's a lot of surface area - in the case of Deneb, the size of the star is comparable to Earth's *orbital* radius.

They should hopefully find this extremely cool. But, you can then impress upon them, there are stars that are even bigger. If you can find Antares among the glow of the Oakland lights (I haven't been able to) its radius goes 4/5 of the way out to Jupiter. The largest star I personally have ever found is Mu Cephei - it's located just below the "box" part of Cepheus and has a radius comparable to the orbit of Saturn. You'll have a tough time getting students to find this one, though.

So, OK, by now you've hammered into them that stars are different temperatures and different sizes. But why's that? This is of course the launching pad to talk about stellar evolution. Talk about how stars start at different masses, condense from a cloud into a dense/hot ball with nuclear reactions at the center; the total mass then determines the internal temperature and pressure and so on which then determines color, luminosity, etc. (Well, OK, it's much more complicated than that, but for now I think going into a discussion of hydrostatic equilibrium and radiative transfer is probably slightly over the top.) Most stars are the direct result of this and fuse H->He at the center - Vega, Altair, the Sun, etc. all fall into this class; Vega and Altair are a bit more massive than the Sun and there slightly brighter / larger / bluer. But not a huge amount. But, you can say, after so many million years, the star starts runs out of hydrogen fuel and gradually gets brighter... and then at some point runs out completely in the center and has to fuse helium, which requires higher internal temperatures to get going and leads to much higher luminosities and a huge expansion in its outer envelope. Whether you want to go on about shell vs. core fusion (which is what *really* causes the gigantic leap in luminosity) is up to you. But I don't really understand the physics behind it very well myself so even though I've mentioned it in the past I'll probably skip it from now on. Either way, be sure to toss in the fun-for-the-whole-family bit about the Sun's and Earth's ultimate future. And then you can cap it off with a discussion of planetary nebulae (mention the Ring Nebula if you're looking at it that night), white dwarfs, and supernovae, neutron stars, and black holes. Mention how we detect black holes (star orbiting a heavy, mysterious, unseen companinon and such) and point in the general direction of Cygnus X-1.


4. Stellar Companions

You've probably been going on for this stuff for about 30 minutes now. The telescope is hopefully working, and some students have seen an object or two, got they needed for their lab points, and left. But, hopefully, you'll still have a crowd - and so, there's still more cool stellar stuff to talk about!

So, go back to the Cal star for a moment, which is two stars orbiting each other. Note that this is actually very typical, and that something like half the stars in the galaxy are in this arrangement. A cool example (especially if Alberio isn't on the viewing list that night or if the telscope really is utterly uncooperative) is Mizar and Alcor. Mizar is the second star from the end of the Dipper's handle, and right above it (as in, a small fraction of a degree) is a fainter but still visible second star called Alcor. Now, technically it seems these aren't a true double, but their distance errors overlap so it is at least possible that they're a very long-period system. So... obviously you should mention that caveat, but still say that they could at least possibly be a double. But! That's not the end of it. Mizar itself is a quadruple-star, even without Alcor - it consists of two pairs of stars, each pair in orbit around the other. And of course the whole thing could be orbiting Alcor, star #5. You can make a silly little demo of this by twirling your fingers around while simultaneously twirling your hands around while simultaneously spinning your arms around your head.

One night when I went over this, a student asked whether double stars actually touch. This added another cool subject to this long list of star-based material - ultra-close binaries that exchange mass (due to expansion at the end of its life causing overfilling of the Roche lobe). Best of example of this is Algol, which is in Perseus, which is... faint and hard to find, but it's right "below" the upside-down W of Cassiopea. It's above brighter Mirphak in the direction of Andromeda. Algol is also an eclipsing binary if you want to mention that.

Unfortunately, there are no bright stars with planets around them that I know of. The G-class dwarfs like the Sun are just too faint to be seen in Berkeley's bright skies...


5. The Milky Way

OK, if students are still interested (and usually they still are) there's plenty more cool stuff to cover. The Milky Way itself is just *barely* visible here; it runs from Sagittarius up through Cygnus and Cassiopea; you can try to draw the arc with your arm and hope they see it. point out that this is a disk of hundreds of millions of stars band circling the sky. Point out its massive size of 100,000 ly or so, compared to the 50-2000 ly distances to the stars you were talking about. An analogy would be if the distance from the Sun to Vega were a cm, it'd be all the way across Campbell courtyard to get to the other side of the galaxy.

So, next point out Sagittarius again, and note that this is the general direction of the center of the Milky Way galaxy. You can note that at first glance it looks pretty ordinary in a regular telescope, but that radio images show huge shock-lobes and jets and other extremely energenic things going on from down that way. And that more detailed observations of the orbits of stars show that they're orbiting something quite small *really* rapidly - something which is, almost certainly, a supermassive black hole of about 3 million times the mass of the Sun. (This really impresses the students.) But point out that relative to the rest of the galaxy the black hole's contribution to the gravity on stars out near the Sun is fairly insignificant. And you can mention that other galaxies have much bigger black holes, some of which are extremely active. (They'll ask questions about this almost guaranteed.)


6. Beyond the Milky Way

This is where we pretty much reach the limit about what you can point out to them. By now all the casually interested students have left and you probably have 5 or so resolute students left, but these are the hard-core types and are hopefully hanging on your every word. They're also probably peppering you with very good and relevant questions (at least half the stuff I mention here is stuff I was asked and never would have thought to mention otherwise) and are eager for more random info. Fortunately, even though we can't see the stuff we're talking about anymore, there's plenty of material left.

So, here you can point out the vicinity of the globular cluster in Hercules, especially if that was on the viewing list for the night, and note that it's a population of nearly primordial stars that orbits the center of the Milky Way galaxy, all about the same age. You can link back to stars to discuss stellar lifetimes here, noting that all the stars there are relatively non-massive and reddish because only "light" stars survive that long.

By now hopefully they've seen the Andromeda galaxy. You can give them the spiel about the light being 2 million years old, and explain that Andromeda is sort of the Milky Way's twin, with the same size (about) and structure. (If you want you can also talk about distance measurement using Cepheids - and Polaris is actually a Cepheid if you need an example.) This makes a good launching point for galaxy morphology - talk about irregulars like the Magellenic Clouds (Southern Hemisphere object, unfortunately; also mention SN 1987a if you wish) and ellipticals like the Virgo galaxy. You can also bring up the different stellar populations in each type of galaxy. You can then talk about galaxy collisions and how some ellipticals may be formed this way from spirals, and point out how Andromeda is on a 5 Gyr collision course with the Milky Way. That can then lead into a discussion about how almost every other galaxy is actually receding from us because the universe is expanding as a result of the big bang, with everything flying away from everything else. And you can bring up the acceleration of this expansion, and discuss the implications Ultimate Fate of the Entire Universe.


6. Q/A

And that's pretty much all I can think of off the bat. You've probably been standing there an hour or so by now, but hopefully there are still a bunch of eager students around asking questions about random stuff - at this point is when I have gotten the questions about relativity, what exactly is involved in being an astronomer, how telescopes work, etc. (The occasional homework question, even.) Which means that you'll probably be standing there even after the GSI handling the telescope has gone home for the night. Which is cool, but be prepared. Eventually the ranks will thin and you can make your escape to go back to... Radiation homework or whatever. :)




Final Comments -

So, as absurdly detailed as this was this is only a rough sketch of how to go about this. Usually I end up jumping from topic to topic, either because I think of one thing based on something else I'd just mentioned or more likely as a result of student questions. I really just cobbled this format together in a couple hours on Friday and it only roughly reflects what I've really been doing. (Copying it exactly probably wouldn't be a good idea anyway; we don't want to give the impression that there's a script we read from in giving these things...)

It's important to be prepared; knowing lots of random facts about different objects is a definite plus. I've mentioned all my favorites but you can use whatever you want, obviously. Highly recommended is Jim Kaler's (of U of I) Star of the Week page (http://www.astro.uiuc.edu/~kaler/sow/sowlist.html) which has loads of awesome facts about pretty much star you can possibly see from Berkeley and plenty you can't. I got almost all the star stuff above from there. If you're really hard-core you can memorize all the names and magnitudes and spectral classes and temperatures and greek designations and luminosities and radii of all the stars of third magnitude and up (something I keep telling myself I'm going to do, and then keep being lazy and not doing it. One of these days...) but it's not really necessary. Still, knowing the bright constellations, along with Arcturus, Polaris, Vega, Lyra, and Altair is a must.

Obviously students aren't going to pick up on everything. But, really, that's not the point - you just want to convince them that the things they can see in the sky are *really freaking cool* (and hot, har har), and maybe remind them of a few key facts as you go along to show that the stuff mentioned in lecture really is important for understanding this cool stuff.

And of course, most importantly, have fun... that's probably the other reason why I've ended up doing 4 of these in the first three weeks! For the most part these are the students that actually care (they decided to come all the way out to Campbell in the middle of the night to do astronomy) and are genuinely interested in what you have to say - so make the most of it!