TVS - H2O

Observatory & Observing Site
How to Get a Key
General Directions to the Site
User Agreement Form
Observatory Status

TVS Club Observatory and Dark Observing Site

The club leases a comparatively dark-sky observing site on a hilltop in the Diablo Mountains south of Livermore and east of San Jose. This is private property, secured and restricted for authorized members and their guests at all times. Authorized (key holding) members can access the site any day of the year. Non-key holding members and the general public must be escorted to, while at, and from the site by key holding members -- NO EXCEPTIONS. At least twice a year we try to hold an "open house" so that new and prospective members can visit the site. But the house is not really completely open. This is just a scheduled opportunity to be escorted to the site.

No one is allowed to drive out to the site without an escort. Anyone wandering out there will not be admitted. In fact, the observatory is a long way from the locked gate at the road, so visitors will not even be noticed by authorized members.

How To Get A Key

To become a key holder:

Make sure you are a member in good standing.
Send in your $20 key deposit with the usual membership application/renewal form. You will be sent a key agreement.
Read, sign, and return the key agreement to the key master. The key master will send you a key (but you still need the combination to get in).
Listen to a verbal orientation given by a board member, preferably the observatory director or the key master. We require the verbal orientation to make sure you have actually heard the rules and procedures for site access, and recognize and agree to try to avoid the kinds of things which have been a problem in the past. This is to protect us from someone signing the written agreement without actually reading it.
After your orientation you will receive the combination and directions to the site.

Most of these steps can be done at a TVS general meeting. It is preferred that the orientation lecture is given as part of an actual visit to the site.

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Directions to the Site

You will not find the directions to Hidden Hill Observatory here, or anywhere else either.

Members are not allowed to tell anyone the directions to Hidden Hill Observatory, even other club members. Only board members can give out directions to the ranch or the site, the exact location (in any form including maps, coordinates, and addresses), the name of the ranch, and the combination to the gate.

You can not meet or wait for anyone at the gate to the ranch. You must meet elsewhere and drive up together with your escort. If you are an escort there is no need to give your guests exact directions before leaving, as they must follow you up there.

Every year we have problems because some well meaning person somehow hears about our site and decides to check it out for themselves. Anyone not knowing proper entry procedure is always a nuisance to the ranch personnel. We have almost lost access to the site because of these problems several times in the past.

We can tell you that it is approximately a 40 to 60 minute drive to the site from Livermore. The road is a mountain road: narrow, windy, steep, unlit, one lane much of the way and there are no services available of any kind. Most of the road does not have any cell phone coverage. If you go, be prepared.

The site is well located for long-exposure astrophotography and deep-sky observing, especially in the southern part of the sky (we can see Omega Centauri). The site is at about 2400 feet in elevation and has an excellent low southern horizon looking over a large dark valley. It is not as dark as a remote location in the Sierra Nevada mountains, of course, but it is one of the darkest locations that is a convenient driving distance from the East San Francisco Bay Area.

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The View to the South from the Observatory. Photo by G. Gottschalk.

The View to the North and East from the Observatory. Photo by G. Gottschalk.

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User Agreement Form and The Rules

Access to the club's dark site is available year round to all members who have put up a $20 key deposit. For each visit there is a $3 per car fee (exact change only). Leave the $3 in the slot in the metal post by the house. Guests of members, and visitors to open houses must be escorted to the site, through the ranch, while on the hill, and back through the ranch to leave.

The club's 17.5-inch equatorially mounted Newtonian telescope, housed in a permanent roll-off roof observatory at the site, is available to patron members.

You will find all the info you need, and the form, by going to our User Agreement site.

The Observatory. The roof slides off to the left. Photo by G. Gottschalk.

The telescope has refigured Coulter optics, an aluminum tube, a Meade DS-16 mount, a Lumicon drive corrector, a Lumicon NGC Sky Vector computer system, a two inch Crayford type focuser, a 12 volt storage battery system with solar powered charger, and various other accessories. This telescope and many of the accessories were donated to the club by member, Dr. Jack Marling, who is also the owner of Lumicon in Livermore.

The 17.5-inch Telescope and the Observatory Director

Patron membership is available to those who have been TVS members for at least one year at an additional cost of $40 per year. We do have a limit on the number of patron memberships available (we are sharing one telescope), but we haven't had to turn down any patron membership applications yet.

The construction of a second permanent observatory building, this time a dome, is underway. This will be a Meade DS-16 telescope, a 16 inch Newtonian equatorially mounted. The dome will be motorized to turn with the telescope. The telescope and building are being donated to the club by member Herb Quick. Our current plans are to make this telescope available to members, when completed, without requiring patron membership.

Looking west we see three tiers of parking/observing sites
and a neighbor's [1] little observatory [2] on the hill [3] on the horizon.

They, being higher, have better seeing, but we have a darker sky.
[1] University of California, Santa Cruz
[2] Lick Observatory with the 120 inch Shane Telescope
[3] Mount Hamilton

There are four permanent piers at the site, which are suitable for mounting Schmidt-Cassegrains and other portable telescopes. There is no electricity or water at the site. The toilet facilities are primitive. There are no recreational facilities. This is private property and we do not want to inconvenience the owners or their neighbors. Hiking, making noise, and smoking are not allowed (there is almost always high fire danger in this area). There is room for parking 12-15 cars on top of the hill, with more parking below (our observing area is entirely on the top of the hill). Access to the ranch from the road is via a gate with a combination lock. Within the ranch, access to the top of the hill is via a short, steep dirt road behind a gate locked with our key lock.

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Observatory Status

The Jack Marling 17.5" telescope

May 3, 1997

I secured a new, exact replacement, motor from the manufacturer and installed it on the telescope. On the advice of Jack Marling, I disassembled the worm mounting assembly first, and found that most of the friction in the entire telescope was in the bearings supporting the worm. The adjustment of a set screw on the assembly provides a very critical balance between friction and backlash. I will try putting a thin teflon washer on this brass on bronze bearing to see if this makes the adjustment any easier.

With the worm assembly removed, the telescope turned very freely and I was able to get a very good balance on the polar (drive) axis.

Anyway, the backlash is adjusted, the motor is mounted, and the drive system is now usable. The polar alignment looks like it is off by a whopping five degrees or so. And we have had no mice in the tube since the pier extension went up.

April 17, 1997

The one RPM motors tested weak. I got a stronger 1/2 RPM motor from Mike Rushford, but which turns the wrong way. By using larger gears, to clear the worm assembly, I was able to mount it on the telescope backwards, but it was not strong enough to turn the telescope.

April 6, 1997

I picked up two more 1 RPM motors at the Livermore ham radio and electronics swap meet this morning. I will test these to see how much torque they produce before taking one up to the site to install.

April 4, 1997

I installed a 1 RPM motor and suitable gears but the motor was defective and could not produce enough torque to turn the telescope. The defective motor and good drive gears and motor mount where then removed.

May 30, 1997 (and summary of recent previous activity)

The solar panel power connector, a plastic-bodied coaxial connector, broke. This connects the solar panel on the sliding roof to the battery charger on the south wall of the observatory. This connector gets yanked out by the wires when the roof is opened. This is not the first time this connector has been replaced. A metal body RCA phono plug was selected for the task this time. (It is a fairly low current application) The metal body is now connected to the roof via a small steel cable which yanks the plug out without stressing the wires and interior components of the connectors.

The 12" pier extension has been installed. The primary purpose of this extension was to allow us to remove about 20 pounds of counterweights from the primary mirror end of the telescope tube, and another 15 pounds of counterweights from the declination axis shaft. The tube was then lowered 6" in the cradle to balance. The dust covers now fit better and, with the bungee cords, should prevent mice from getting into the telescope tube. A side effect of this change is that although the telescope mount has been raised 12", the eyepiece is now only 6" higher than before. The telescope can now "see" much of the southern horizon over the observatory walls.

The polar alignment is probably way off, and we will probably have to disassemble the entire mount to widen some mounting holes in the pier to provide enough adjustment.

The broken spider vane connectors on the 17.5" telescope have been replaced. The scope was then completely recollimated, including the focuser and diagonal mirror.

It was noticed that there was some flex in the focuser (JMI NGF-2) in some positions when under moderate load. For example, similar to the normal configuration with two extension tubes and the 13mm Nagler eyepiece. This was enough flex to take the telescope out of collimation by at least 2mm (the diffraction limit requires collimation to better than 0.5mm). So the focuser was disassembled and tightened up then mounted in a different orientation on the tube. This should minimize focuser flex for most orientations of the telescope commonly used. Flex in the eyepiece extension tubes was also noted. Tightly securing ALL of the thumbscrews (some were missing) removed this source of flex.

After all this tweaking, yanking on the eyepiece tube still produced some noticeable flex. It was then observed that the telescope tube was flexing where the focuser is mounted. Some kind of stiffeners will have to be built and installed. This has not yet been fixed. I'm sure the present situation is way better than it ever was for the years with the cardboard tube, but it still can be improved.

The drive is still not working. I now have a 1 RPM motor and suitable gears to replace the previous 0.5 RPM motor and gears. I need to modify the mounting bracket to accept the different spacing required by the different size motor and different gear ratio. This should be fixed by April 5, 1997.

Ongoing/future projects

1. Tweak the tube balance so that it balances better with the 13mm Nagler eyepiece installed.
2. Fix the drive
3. Polar alignment
4. Build and install tube stiffeners to prevent flex near the focuser.
5. Build a raised floor to restore previous ergonomics
6. Clean inside of tube (residue of 4 or 5 mouse families)
7. Blacken some parts inside the tube
8. Add thermal insulation and stray light baffling to inside the tube
9. Mount a Telrad
10. Fix the observatory red lights
11. Maybe clean the mirrors, but I don't think they really need it yet
12. Seal some of the mouse nesting locations in the framework of the building
13. Build some kind of weatherproof bulletin/notice board for all users of the site

The Herb Quick 16" telescope.

January 2000: Construction of the dome building is complete. The fiberglass dome is mounted and functional. The telescope pier is in place and the telescope will soon be mounted. It should be ready for use when the electrical system is installed.

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	H2O (Hidden Hill Observatory)

		Observatory & Observing Site How to Get a Key General Directions to the Site User Agreement Form Observatory Status TVS Club Observatory and Dark Observing Site The club leases a comparatively dark-sky observing site on a hilltop in the Diablo Mountains south of Livermore and east of San Jose. This is private property, secured and restricted for authorized members and their guests at all times. Authorized (key holding) members can access the site any day of the year. Non-key holding members and the general public must be escorted to, while at, and from the site by key holding members -- NO EXCEPTIONS. At least twice a year we try to hold an "open house" so that new and prospective members can visit the site. But the house is not really completely open. This is just a scheduled opportunity to be escorted to the site. No one is allowed to drive out to the site without an escort. Anyone wandering out there will not be admitted. In fact, the observatory is a long way from the locked gate at the road, so visitors will not even be noticed by authorized members. How To Get A Key To become a key holder: Make sure you are a member in good standing. Send in your $20 key deposit with the usual membership application/renewal form. You will be sent a key agreement. Read, sign, and return the key agreement to the key master. The key master will send you a key (but you still need the combination to get in). Listen to a verbal orientation given by a board member, preferably the observatory director or the key master. We require the verbal orientation to make sure you have actually heard the rules and procedures for site access, and recognize and agree to try to avoid the kinds of things which have been a problem in the past. This is to protect us from someone signing the written agreement without actually reading it. After your orientation you will receive the combination and directions to the site. Most of these steps can be done at a TVS general meeting. It is preferred that the orientation lecture is given as part of an actual visit to the site. Return to Top Directions to the Site You will not find the directions to Hidden Hill Observatory here, or anywhere else either. Members are not allowed to tell anyone the directions to Hidden Hill Observatory, even other club members. Only board members can give out directions to the ranch or the site, the exact location (in any form including maps, coordinates, and addresses), the name of the ranch, and the combination to the gate. You can not meet or wait for anyone at the gate to the ranch. You must meet elsewhere and drive up together with your escort. If you are an escort there is no need to give your guests exact directions before leaving, as they must follow you up there. Every year we have problems because some well meaning person somehow hears about our site and decides to check it out for themselves. Anyone not knowing proper entry procedure is always a nuisance to the ranch personnel. We have almost lost access to the site because of these problems several times in the past. We can tell you that it is approximately a 40 to 60 minute drive to the site from Livermore. The road is a mountain road: narrow, windy, steep, unlit, one lane much of the way and there are no services available of any kind. Most of the road does not have any cell phone coverage. If you go, be prepared. The site is well located for long-exposure astrophotography and deep-sky observing, especially in the southern part of the sky (we can see Omega Centauri). The site is at about 2400 feet in elevation and has an excellent low southern horizon looking over a large dark valley. It is not as dark as a remote location in the Sierra Nevada mountains, of course, but it is one of the darkest locations that is a convenient driving distance from the East San Francisco Bay Area. \| The View to the South from the Observatory. Photo by G. Gottschalk. The View to the North and East from the Observatory. Photo by G. Gottschalk. Return to Top User Agreement Form and The Rules Access to the club's dark site is available year round to all members who have put up a $20 key deposit. For each visit there is a $3 per car fee (exact change only). Leave the $3 in the slot in the metal post by the house. Guests of members, and visitors to open houses must be escorted to the site, through the ranch, while on the hill, and back through the ranch to leave. The club's 17.5-inch equatorially mounted Newtonian telescope, housed in a permanent roll-off roof observatory at the site, is available to patron members. You will find all the info you need, and the form, by going to our User Agreement site. The Observatory. The roof slides off to the left. Photo by G. Gottschalk. The telescope has refigured Coulter optics, an aluminum tube, a Meade DS-16 mount, a Lumicon drive corrector, a Lumicon NGC Sky Vector computer system, a two inch Crayford type focuser, a 12 volt storage battery system with solar powered charger, and various other accessories. This telescope and many of the accessories were donated to the club by member, Dr. Jack Marling, who is also the owner of Lumicon in Livermore. The 17.5-inch Telescope and the Observatory Director Patron membership is available to those who have been TVS members for at least one year at an additional cost of $40 per year. We do have a limit on the number of patron memberships available (we are sharing one telescope), but we haven't had to turn down any patron membership applications yet. The construction of a second permanent observatory building, this time a dome, is underway. This will be a Meade DS-16 telescope, a 16 inch Newtonian equatorially mounted. The dome will be motorized to turn with the telescope. The telescope and building are being donated to the club by member Herb Quick. Our current plans are to make this telescope available to members, when completed, without requiring patron membership. Looking west we see three tiers of parking/observing sites and a neighbor's [1] little observatory [2] on the hill [3] on the horizon. They, being higher, have better seeing, but we have a darker sky. [1] University of California, Santa Cruz [2] Lick Observatory with the 120 inch Shane Telescope [3] Mount Hamilton There are four permanent piers at the site, which are suitable for mounting Schmidt-Cassegrains and other portable telescopes. There is no electricity or water at the site. The toilet facilities are primitive. There are no recreational facilities. This is private property and we do not want to inconvenience the owners or their neighbors. Hiking, making noise, and smoking are not allowed (there is almost always high fire danger in this area). There is room for parking 12-15 cars on top of the hill, with more parking below (our observing area is entirely on the top of the hill). Access to the ranch from the road is via a gate with a combination lock. Within the ranch, access to the top of the hill is via a short, steep dirt road behind a gate locked with our key lock. Return to Top Observatory Status The Jack Marling 17.5" telescope May 3, 1997 I secured a new, exact replacement, motor from the manufacturer and installed it on the telescope. On the advice of Jack Marling, I disassembled the worm mounting assembly first, and found that most of the friction in the entire telescope was in the bearings supporting the worm. The adjustment of a set screw on the assembly provides a very critical balance between friction and backlash. I will try putting a thin teflon washer on this brass on bronze bearing to see if this makes the adjustment any easier. With the worm assembly removed, the telescope turned very freely and I was able to get a very good balance on the polar (drive) axis. Anyway, the backlash is adjusted, the motor is mounted, and the drive system is now usable. The polar alignment looks like it is off by a whopping five degrees or so. And we have had no mice in the tube since the pier extension went up. April 17, 1997 The one RPM motors tested weak. I got a stronger 1/2 RPM motor from Mike Rushford, but which turns the wrong way. By using larger gears, to clear the worm assembly, I was able to mount it on the telescope backwards, but it was not strong enough to turn the telescope. April 6, 1997 I picked up two more 1 RPM motors at the Livermore ham radio and electronics swap meet this morning. I will test these to see how much torque they produce before taking one up to the site to install. April 4, 1997 I installed a 1 RPM motor and suitable gears but the motor was defective and could not produce enough torque to turn the telescope. The defective motor and good drive gears and motor mount where then removed. May 30, 1997 (and summary of recent previous activity) The solar panel power connector, a plastic-bodied coaxial connector, broke. This connects the solar panel on the sliding roof to the battery charger on the south wall of the observatory. This connector gets yanked out by the wires when the roof is opened. This is not the first time this connector has been replaced. A metal body RCA phono plug was selected for the task this time. (It is a fairly low current application) The metal body is now connected to the roof via a small steel cable which yanks the plug out without stressing the wires and interior components of the connectors. The 12" pier extension has been installed. The primary purpose of this extension was to allow us to remove about 20 pounds of counterweights from the primary mirror end of the telescope tube, and another 15 pounds of counterweights from the declination axis shaft. The tube was then lowered 6" in the cradle to balance. The dust covers now fit better and, with the bungee cords, should prevent mice from getting into the telescope tube. A side effect of this change is that although the telescope mount has been raised 12", the eyepiece is now only 6" higher than before. The telescope can now "see" much of the southern horizon over the observatory walls. The polar alignment is probably way off, and we will probably have to disassemble the entire mount to widen some mounting holes in the pier to provide enough adjustment. The broken spider vane connectors on the 17.5" telescope have been replaced. The scope was then completely recollimated, including the focuser and diagonal mirror. It was noticed that there was some flex in the focuser (JMI NGF-2) in some positions when under moderate load. For example, similar to the normal configuration with two extension tubes and the 13mm Nagler eyepiece. This was enough flex to take the telescope out of collimation by at least 2mm (the diffraction limit requires collimation to better than 0.5mm). So the focuser was disassembled and tightened up then mounted in a different orientation on the tube. This should minimize focuser flex for most orientations of the telescope commonly used. Flex in the eyepiece extension tubes was also noted. Tightly securing ALL of the thumbscrews (some were missing) removed this source of flex. After all this tweaking, yanking on the eyepiece tube still produced some noticeable flex. It was then observed that the telescope tube was flexing where the focuser is mounted. Some kind of stiffeners will have to be built and installed. This has not yet been fixed. I'm sure the present situation is way better than it ever was for the years with the cardboard tube, but it still can be improved. The drive is still not working. I now have a 1 RPM motor and suitable gears to replace the previous 0.5 RPM motor and gears. I need to modify the mounting bracket to accept the different spacing required by the different size motor and different gear ratio. This should be fixed by April 5, 1997. Ongoing/future projects 1. Tweak the tube balance so that it balances better with the 13mm Nagler eyepiece installed. 2. Fix the drive 3. Polar alignment 4. Build and install tube stiffeners to prevent flex near the focuser. 5. Build a raised floor to restore previous ergonomics 6. Clean inside of tube (residue of 4 or 5 mouse families) 7. Blacken some parts inside the tube 8. Add thermal insulation and stray light baffling to inside the tube 9. Mount a Telrad 10. Fix the observatory red lights 11. Maybe clean the mirrors, but I don't think they really need it yet 12. Seal some of the mouse nesting locations in the framework of the building 13. Build some kind of weatherproof bulletin/notice board for all users of the site The Herb Quick 16" telescope. January 2000: Construction of the dome building is complete. The fiberglass dome is mounted and functional. The telescope pier is in place and the telescope will soon be mounted. It should be ready for use when the electrical system is installed. Return to Top

H2O (Hidden Hill Observatory)