Tuesday, February 7, 2012
7 February 2012
Sunday, February 5, 2012
5 February 2012
seeing was very poor today. There was continuous boiling across the entire disk of he sun. I picked out two groups that I made to be close to the solar equator, a large one to the north and a smaller one to the south. It turns out they were both north. Phase rotation bit me. This close to noon I didn't think that would be an issue. The smaller spot kept disappearing in the boils and I wasn't able to get focus on he large spot so it isn't worth doing a full report on the observation.
After I finished up the solar observing I started to zero in the new Sun finder but found that it was dead on. Some of the screws are stiff enough in the nuts that I don't think it will ever come out of alignment in transport or handling.
This has been a longterm project. It started when I got my Celestron C70 Mini Mak Spotting Scope (Mini Mak for short).
I had been trying to figure some way to hose clamp the foot to the scope but wasn't making any progress. Just clamping the shoe to the scope wouldn't work because the foot is taller than the shoe. I bought the hose clamps anyway since I didn't see any other way to affix the shoe to the scope.
Then I remembered the laser at NYC Resistor. People are always making boxes out of light wood on it. So I decided to make a box out of plastic that would háve slits near the top edge for the hose clamps to pass through and holes in the bottom where the shoe would be bolted on. The box would be mounted open top down and have concave ends to accommodate the round of the scope. On my first attempt I didn't get the dimensions of my end pieces right and the plastic I used was too thin to take the stress of being clamped but it held the finder in place and I was able to use it to point the scope. Proof of concept.
For my second attempt I used thicker plastic and doubled it up in places to reinforce possible weak points. The reinforcement created another problem. Now the sides of the box were so thick that only the inside edges made contact with the tube and when I clamped it to the scope it cracked anyway. The crack was repairable with the plastic solvent and I used a Dremel to bevel the inside of the box for a better fit. That finished off that phase of development. I have used it a lot with success and having the box under the foot raises the sight to a more comfortable height above the scope tube.
Phase two was to come up with a foot to fit into the shoe and onto which the actual finder would be mounted.
I briefly considered using acrylic since I would be able to cut it on the laser with minimal assistance. But that would require bevel cuts which are not possible on the laser and I didn't think plastics would hold up to the repeated compression of the retaining screw.
Next I looked into Delrin and aluminum. Delrin looked promising because it appeared to be softer than aluminum, is dimensionally stable, and is machinable. But researching it I found that I would have to buy too much of it to be cost effective. So I switched over to aluminum and found the same cost issue there. Raphael at NYC resistor said he has some aluminum that we could use. He was also going to help me with the milling since I know nothing about CNC (computer numerical control) machines.
I started out designing the 3D foot in Google SketchUp. Then I found that we couldn't export the object in the digital format required by the milling machine. So I switched over to designing it in 2D in Inkscape. After getting it designed we had to get a plugin to export the proper file format. But we weren't able to turn it into 3D so I ended up copying and pasting one copy of the file for each pass of the router. After all that was don and Raphael and I coordinated time on the mill it took a couple of hours to get the piece cut. A few more hours were consumed in tapping the screw holes and figuring out what needed to be adjusted to get it to fit properly.
I had searched the Web for finders and found the "A Collection of Solar Finder Designs" out of Germany. I liked design #14 by Robert Pudlo but working in aluminum would require more milling and getting the end pieces bent in the right place so they are properly aligned would be difficult for me. But I could make something like it out of plastic.
To get around problems of not getting things perfectly aligned or not having the finder aligned with the scope I wanted to build in a collimation mechanism. I knew left right alignment could be easily taken care of. I was going to use two mounting screws aligned on the long axis of the finder. Making one elongated crosswise would allow that end of the finder to be swung a bit sideways. Up-down alignment was harder for me to figure out. I ended up designing a double base with a hinge at the front. The bottom base piece would be mounted to the foot with the front end lower than the back. A hinge would be mounted to the front of the bottom base and then the top base mounted to the other half of the hinge laying on top of the bottom base. Near the back end of the base a screw would pass through the top base, through the center of the spring, through the bottom base and into a captive nut. When the screw was tightened it would pull the top base down and the Sun spot would go up on the target. The reverse for loosening the screw. It wasn't going to be pretty but it seems like it should work. Then I decided to use a similar technique for left-right adjustment. It was getting very ugly now but should have worked.
I talked to one of the MakerBot Industries principles to get an evaluation of the design and he sent me back to see the guys in "Tool Town" who do a lot of design work. The guy who was there was the French guy. It took a long while to try to make him understand what I was trying to accomplish and his solution involved redesigning the back end to include electronics which I didn't want to do. The American showed up and after a lot of translation he started to draw something and said collimation and it instantly clicked. What I wanted to do was to build something analogous to a Newtonian mirror cell.
I designed the finder while I was working on the foot but it was still a couple of months before I had it to the point where I was satisfied enough with it to go to the laser.
I found some captive nuts that you press into your material while searching McMaster-Carr. They are working but it was a real pain getting them pressed into the plastic. I ended up using a huge C clamp. The major downside was that there wasn't enough plastic around the holes they were pressed into to absorb the stress and all three holes cracked in at least one place. I fused them with the liquid acrylic adhesive.
My screw holes for the mounting screws were not big enough so I had to file them out a bit. I guess I didn't get them filed evenly because the finder wasn't sitting square on the foot. I drifted one hole and things looked better. I mounted the mask and target to the back piece. For some reason which I can't explain that caused the bagk to bend in toward the front. I adjusted the screws to where things looked "right" and when I tried it out found that it was spot on. I have used it three times now and haven't had to make any adjustments.
I tried to find Venus without any success. Before heading out I checked her location relative to the Sun and swept the area as well as the area left, right, above and below where I thought she should be. Initially I had no idea what distance my binocular was focused on so I held the solar filter in front of one lens and focused on the Sun. I still wasn't able to locate the planet.
The NOAA forecast for tonight was for a cloudless sky so I sent email to Peter saying I would be heading for TotL after dinner. A couple of minutes later I got a similar email from him saying he was just arriving at Drip Rock and only intended staying for a couple of hours. I figured he might be leaving or gone by the time I passed there on my way to TotL but when I arrived two hours later he was still there.
We observed together for three hours concentrating on the area of the terminator around gassed. In his refractor we located Rima Snelius and Rima Gaseni and the mountains on the south rim of ___ looked very nice.
I started out using the zoom lens on my Mini Mak but when we got into comparing features between the two eyepieces I switched over to the fixed focal length eyepieces from the mortar hoping ghat I would be able to use higher magnification. I hound that 50x was OK but conditions did not support 83x on that scope. Peter was able to use a short eyepiece with a Barlow on his scope giving us some tight views.
late in the session Steve and Gracie Beltser arrived. We looked at the Great Orion Nebula in the Mini Mak at 50x with and without my UHC filter. Adding the filter extinguished the trapezium but greatly increased the nebulosity. Steve asked if we had ever seen the nebulosity in the Pleiades and we talked about our recent experience of observing with the filter at Custer Institute. I dropped my magnification to 18x and with the UHC installed he was able to see nebulosity around several of he stars.
For me this session lasted from 1930 EST until 2230 EST.
Thursday, February 2, 2012
2 February 2012
Groundhog Day
I was up at 0400 this morning to make the trek to the Staten Island Zoo to see their groundhog (woodchuck), Staten Island Chuck, make his prediction for the remainder of the winter season.I had no idea where I was going so getting there in the dark wasn't fun. The PA on the bus was the usual inaudible. It sounded like the driver wasn't taking the telephone handset out of the cradle but he was fulfilling the ADA mandate by keying it and talking at it. Eventually I heard something that sounded like it might be my stop and saw the golden arches that reminded me there was a nearby McDonalds so I gave it a try.
It was a media zoo when I got there but the gates were not open for the public yet. There was only one family there ahead of me and they opened the gates early just after I arrived so I got in before most of the public arrived and got a space against the barricade where I would have a view of the rodent's appearance.
Chuck had a large wooden house up on stage with a John Deere miniature wind wheel and full electronic weather station behind it. There is a little trap door in the front of the house and when they opened it there was a straw filled bucket that they had Chuck crammed into waiting for his freedom. It is no wonder he took a chunk out of the mayor's hand three years ago.
They had the stage lit up like daytime for the TV cameras so there was no way SI Chuck wasn't going to cast a shadow even though it was overcast and the sun wasn't high enough when they let him out even if the clouds hadn't been there. But the mayor announced that we would be having an early spring, and just in case Chuck was wrong (he and his predecessor SI Chucks have an 80% success rate) the City has plenty of salt stockpiled.
After all the speeches the door is opened and Chuck tumbles out to be immediately scooped up by a handler who hands him off to the mayor who this year is wearing heavy leather work gloves. Chuck doesn't look any too happy about all of this.
The temperature topped out at 62° yesterday and it wasn't cold enough this morning that I needed gloves but it is only supposed to be in the 30s and 40s for the rest of the week so it looks like that early spring is a little ways off. Still it seems like it has been a mild winter and we have only had two snowfalls so far.
After the event I walked down to the North Shore and along it back to the ferry. The last time I was out there for a sea chantey sing I thought I had seen some new-to-me birds and have been wanting to get back there to try and identify them. I came up with four new ducks and one west coast seagull.
Tuesday, January 31, 2012
31 January 2012
| Observing Location | Riverdale Metro North Station adjacent to the southbound platform Westchester Co, NY Lat: 40° 54.?43' by GPS, 40.905733 by Google Maps Long: -73° 54.888' by GPS, -73.913453 by Google Maps  | ||||||||||||||||||||||
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| Observational Period | 2000-2115 EST | ||||||||||||||||||||||
| Atmospheric Conditions |
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| Instruments | Celestron C70 Mini Mak Spotting Scope with stock 27x-75x zoom lens - Charlie | ||||||||||||||||||||||
| Observing Party | Charlie Ridgway |
Tonight was the grazing occultation of ZC465 (Botein, δ Ari). NOAA had been predicting 50% cloud cover followed by rain and/or snow during the overnight hours but late this afternoon when I made a last minute check the cloud cover forecast had dropped to 15%. Low values usually mean clouds low on the horizon and clear overhead and since the Moon was going to be up around 50° altitude I thought it was worth taking a chance on it even though it meant a train ride out of The City.
I caught the last Peak train to arrive early so I would have time to find a suitable observing location. I had planned to observe from the NE corner of the Metro North parking lot at Riverdale since it would be out of the flow of departing cars even though Derek had advised that the southern end of the parking lot would likely yield more events. They yesterday it dawned on me that I could set up on the southbound platform since there were no scheduled departures until after the event would be over. In the satellite imagery there appeared to be a ramp from that platform down to grade and an adjacent roadbed and possibly to the river but I had no knowledge of whether it was accessible to the public. On reaching the ramp I found that it was unsecured and there were signs there indicating that river life in the area was toxic so I figured it was a public access. The roadbed there was fenced and gated and although maintained it did not appear to have been used recently. On the other side of the crossing was a cement footpath heading south along the river. I went to the northern end of the walk and set up there but quickly moved farther north along a dirt track to what I estimated to be the 0.55km S graze line which Derek had recommended.
It was perfectly clear when I got there but in 20 minutes a deck of clouds from the NW was encroaching on the Moon and shortly thereafter the whole western sky was filled with broken clouds. They weren't thick enough to obscure the Moon but they did block out δ Ari entirely. I was able to see the star through the edges of the clouds and in the gaps between clouds but the gaps were muck smaller than the clouds and were moving fast.
A few times the wind gusted up to 8 mph and caused the scope to jump around. I also learned the difference between light rail and non light rail. I had no trouble observing when the electric commuter trains were passing but when the diesel powered commuter, Amtrak and freight trains were passing the scope danced. There were a lot of through trains going past the station on the center tracks and observing from the platform probably would not have been possible do to scope shake when they were passing.
This is my first time attempting a graze with my backpack observatory so I learned all the shortcomings. The Mini Mak was up to the task but with the Moon this high I had to bend over and look up to see through the eyepiece. I probably would have been better off if I had brought one of my observing stools even though I have trouble finding a place for my knees when I am sitting at the tripod. I had been listening for WWV or CHU time signals during the week with my handheld ham radio but never heard anything. That was also my experience with my former handheld although I could pick up the signals on a portable Grundig Yachtboy short wave receiver. I was able to receive intermittent CHU signals on 3.330 MHz but it required a lot of moving the radio around when the signal dropped. The signal to noise ratio was very low so I was often listening to as much or more static as I was time signals. I was recording the event on my cheap Olympus digital voice recorder. I have found that this device is sensitive enough to pick up my mumbled voice when it was in a breast pocket inside my down parka. But today it particularly liked the static roar on the ham radio and set it's audio level for that sound source even though my mouth was closer to the microphone. I have listened to the recording to try to time events with the chronometer in my Gill RegattaMaster wristwatch but I don't know how to properly use the lap feature and I can't figure out how to pause the voice recorder playback. I will need to get the audio into my MacBook where I can work with it in Audacity or Garage Band. [3Feb12 Done. I plugged the earphone out of the voice recorder into the mic in of the computer and recorded the signals in Audacity. Then I sequentially clipped the recording until all I had left was a file starting at 0210 UT and ending after I identified separation from the limb. It was very easy to use the Audacity time scale to get the offset from the beginning of the recording and add that to the 0210 UT start of the recording to get event times. It looks like there is an error of about 0.5 seconds, minus I think, using this procedure. So now all the timing has been reduced.]
It was a little frustrating observing this event because I knew there was more going on than what the clouds were permitting me to see. If I hadn't had prior graze experience I probably would have missed much of what little I did see.
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It appears that this is the only observing I have done during the month of January.
Friday, January 27, 2012
27 January 2012
There were two second grade classes involved, one that is taught in French and the other in Spanish. We made our presentation is English. Mostly it was a show and tell. The students were attentive and well informed but at the end when Peter was using his Power Point presentation to summarize what we had talked about the dynamic abruptly snapped. Half of the class stood in front of him looking at the laptop and the other half gathered around me and the telescopes.
Peter had brought his refractor and his Newtonian reflector and I my Mini Mak solar observing setup. All of the kids want to look through all of the scopes and binoculars. They were particularly interested in looking in the objective ends. It was cloudy out so we set the binoculars and Mini Mak up in front of the windows looking at trees and buildings across the street. Everyone had to look through the eyepiece with their hands wrapped around it and wrench the back end of the scope to look at something different.
It was a positive experience for both us and the kids but I wouldn't want to have to do it all day every day.
Friday, January 13, 2012
13 January 2012
I was thinking a long barb was 10 mph and a short barb 5. I went searching the web and found this NOAA site that gives some basic information on the graphical forecasts that I haven't come across before. It says 10 & 5 mph respectively for the long and short barb a and 50 mph for a flag.
But on further search I found this NOAA site on synoptic charts. It says 10 & 5 but that the units of measure are expressed in knots. That seems to bring the barbs into alignment with the plotted values but using two units of measure for the same point make the chart confusing.
I am going to have to make another chart relating wind barbs, wind speed in mph and knots, and the Beaufort Scale. Hopefully there will be some correspondence there.
Friday, January 6, 2012
6 January 2012
Observer's Guide 2012 graphic
Observer's Guide 2012 graphic
Observer's Guide 2012 graphic
I checked on the IOTA web page yesterday and downloaded the bright star occultation predictions for NYC for the year and reviewed it on the way out to hacking and found that there are few good events for us this year. I don't remember seeing any really bright stars listed but for most of the events the Moon is greater than 25% illuminated. One event I did mark off as of possible interest had a note saying that the event would be a graze 18km to the north of NYC which it turns out is defined at the east side of 6 Ave between 37 and 37 Streets. It was #16 that I had identified.
I downloaded Occult and tried to figure it out but I have forgotten a lot of the little I used to know about the program. Poking around on the IOTA site I found a site that was supposed to have interactive maps but they are all static and don't have this event. I found Derek Breit's site which has some detailed maps but not for this event. He will take requests so I emailed him expressing my interest and very shortly got an email back pointing me to a page that had listings of centerline locations across the country and a limb map which I used to get out of Occult, but his is much more detailed.
Breit Ideas graphic
Derek's sent me a link to his page with an interactive map. I had hoped to be able to observe from TotL with Peter or maybe from The Cloisters if I needed to be closer to the centerline. Plugging in the most favorable offset from the centerline I found that I needed to be ~0.5km away so that means I am going to have to go to Westchester. [3Feb12 To get a graze position south of the graze centerline you need to enter a + value for one of the lines. I then add a big - value for the other line to get it out of the way so there is no confusion.]
Breit Ideas graphic
Breit Ideas graphic
My initial thought was that I would take the train to Riverdale and observe from the north end of the MTA parking lot but then realized that I was using the wrong offset line. For a northern limb graze your offset is a minus value and that line is north of the graze centerline. So recalculating it looks like I need to go to Ludlow and then walk south to a school ballfield.
Breit Ideas graphic
Google Maps graphic
This doesn't look like a great location but in the satellite image I don't see any light pole shadows and the Moon will be up around 50° so trees or buildings getting in the way shouldn't be a problem.
Sky Safari graphic
[3Feb12 Derek subsequently advised me that the best location would be 0.55 km S of the centerline which puts me back in the Riverdale parking lot but at a choke point for traffic.]
For what it's worth, dryday.com is predicting that this event will fall during a dry period.
dryday.com graphic
And Peter isn't available so I am on my own on this one.