Celestron C6 Hyperstar SPC900NC Orion and Flame Nebulae

Orion Nebula M42 80x10s 13.3min 9xDark

Flame Nebula 135x10s 22.5min No Dark

Moon 747 Stacked Frames in Registax

Equipment lists:

Celestron C6 SGT/SCT

Nexstar SLT Mount

Hyperstar Lens FL290mm f1.9

Baader Neodymium Filter

SPC900NC LX/Amp off

Stacked with DSS

It was a very clear night but very cold as well. The moon was 90% illuminated as shown above. The hyperstar collimation was brought to the default position; screwed down all the way back. It seems to be rather acceptably collimated with the default. The moon looks good. The starts in the nebulae photos looks okay as well.

There seems to a problem with the dark frame calibration this time. A total of 29 dark frames from a group of 9 and 20 frames were taken but if all of them were used for calibration, vertical streak would appear on the images. So, only 9 dark frames were used for calibration on Orion Nebula while none for Flame Nebula. Some forum suggested that the streaky image is a result of mismatch dark frames, i.e different temperature between the light and dark frames. This is very much possible as light/dark frame are taken at different time, sometimes at 20-30 minutes apart. Some suggested not to use dark frame. Even without calibration using dark frame, there seems not that much noise after all except for one or two visible hot pixels. The frame capture sequence is as follow, Orion, Dark 9, Orion, Dark 20, Flame. 

Taxi Fare : Hazel Farm, University of Surrey, Guildford Town, Train Station

Hazel Farm to Guildford Cathedral / University of Surrey : £8.40 day time
Guildford Train Station Main Entrance to Hazel Farm :  £10.40 after 11PM
Guildford Train Station the Other Entrance to Hazel Farm :  £12+ or  £11+ (can't remember exactly) after 11PM

The fare after 11PM is about 50% more than before 11PM as told by the taxi driver. Both taxi and private hire car are charging the same fare as the fare is set by the borough council.

Telescope Arduino Stepper Motor Focuser Current Rating using 28BYJ-48 5V and 12V

The motor focuser is used to control the focusing knob of the Celestron C6 SCT. The controller board is Arduino Nano and the stepper motors is the 5V or 12V versions of 28BYJ48. It seems that the 12V version is using much less current as compared to the 5V version when supplied with 12V. It also should generate less heat.

Current Measurement
Arduino Nano and Driver Board : 40 mA

28BYJ48-5V supplied with 12V (inc arduino nano and driver board)
Max. speed (Delay@750µs) : 380 mA
Min. speed  (16000µs) : 510 mA

28BYJ48-12V supplied with 12V (inc arduino nano and driver board)
Max. speed (900µs) : 150 mA
Min speed (>10000µs) : 180 mA

The delay in microsecond as shown in the parentheses refers to the delay when changing the step of the stepper motor. The shorter the delay, the faster the motor will spin. From stall, the maximum stepping rate for the two motors are different and it is faster in the 5V version as shown above. Once the motor is running, the delay can be reduced slightly to achieve faster spinning. As for the 12V version, ~17RPM is achieved with 850µs delay and ~19RPM with 750µs delay.

Nexstar SLT Current Rating Measurement

Measured Current for Nexstar SLT without Load
Idle : 150mA
Altitude slewing only (Rate 9) : 330mA
Azimuth slewing only (Rate 9) : 90mA
Azimuth slewing only (Rate 6) : 30mA
Total current at Rate 9 slewing speed on both axes (Idle+altitude+azimuth): 570mA
Total current when tracking : 190mA

The real max. current flow is lower than the 750mA as suggested by the manufacturer. Slewing at lower speed uses less current then faster speed. With Celestron C6 SCT as the load, the azimuth current stays about the same (~10mA increase). When going up and down in the altitude axis, 30mA higher and 20mA lower current are measured, respectively. The telescope is not in perfect balance and this might cause the differences. The difference in the azimuth and altitude current suggest that the motors used are different. The total current when tracking is only 190mA which is not that much. Slewing seems to be eating the battery the most especially in the altitude axis.

UK License (DVLA) Address Change : How Long?

Any changes to the permanent address needs to be informed to DVLA. As a consequence, the plastic photocard and green Counterpart Driving Licence need to be updated as well. On the front page of the green Counterpart Driving Licence , fill in the new address, sign and date at the "Changes to your permanent address, ..." section. Together with the plastic photocard driving licence, send them to DVLA, Swansea, SA99 1BN (That's right. A very short and simple address.). The photo in the database will be used. So, new photo is not need. There is no application fee. According to DVLA D100 booklet on page 8, it is permissible to drive while waiting for the new licence to arrive. If renting a car from Kendall Guildford without the license, bring some other ID such as a passport and they will be able to check with DVLA except on Sunday for a fee of £5.
When I updated my address, the whole process took 14 days including the day it was sent to DVLA and delivered back to me. It was sent using Royal Mail Special Delivery (RMSD) envelope. I also provided them with another prepaid RMSD with self return address and they used it. RMSD is a next day delivery service. It uses different channel and is not mixed with 1st and 2nd class mails.

University of Surrey WiFi Setting Android

WiFi setting as below:
SID: UOS_SECURE
Security: 802.1x EAP
EAP method: PEAP
Phase-2 authentication: MSCHAPV2
Identity: Surrey username without @
Password: xxx

There are other wifi networks as well in the university: UOS_OPEN, UOS_VISITOR and eduroam.

Second trial with C6 Hyperstar SPC900NC

Orion Nebula/M42 (7.6 minutes) 

Flame Nebula/NGC2024 (3.8 minutes)

Horse Head Nebula/IC434 (5.07 minutes 16x19s* Max gain)

16x19s 5.07min 14xdark Max Gain

Seems to be having more success this time.

Equipment lists:
Celestron C6 SGT
Nexstar SLT Mount
Hyperstar Lens FL290 f1.9
Baader Neodymium Filter
SPC900NC LX/Amp Off Mode
Stacked with DSS

Starry Dave : Dave's Focus Meter

Dave's Focus Meter

"Dave’s Focus Meter gives you a visual indication of just how sharp your current video screen or image is. It will work with any video source, live or recorded, and any image format. It is designed for astronomy, microscopy, security and any area where precise focus is important."

A percentage score is given to the current image as an indication of the focus accuracy. As the focus is changed, the score will be given relative to the intial image score. A better image will receive higher score which is capped at 100%. By going in and out of focus, the percentage score will increase to a maximum score and then decrease. The maximum score is achieved when image is sharpest which indicates the correct focus point. 

I tested this out on a distance wall and  the software gave the correct indication of the focus level. It can control a ASCOM motor focuser as well. However, the autofocusing using ASCOM platform is not completed yet. It shouldn't take long for the author to finish it. An interesting piece of software to hep with the focus. But, I'm not sure if it will work on a star?? The download link is provided in the user manual.

Surrey365 Exchange Server Email Setting

Add account > Exchange
Manual setup
Email address > a.abc@surey.ac.uk with password
Username > \aabc1234@surrey.ac.uk
Server > m.outlook.com Updated 04/02/2014: outlook.office365.com

UK VAT Refund with Student Visa

Based on the experience of my friend and I in purchasing an item from Carphone Warehouse and getting the VAT refund at the Heathrow airport. For student with valid visa, obtain a letter from the university stating that you have finished with your studies. Items bought within the last three months of departure are eligible for VAT refund. Make sure the forms have been filled in completely for a more pleasant experience at the airport.

At the Carphone Warehouse
The Guildford store did not have form to issue the VAT refund receipt. They suggested that we try in London. So, we went to Oxford St. branch and they were able to issue the VAT refund receipt. No identification was needed there (At mothercare, the shop asked for my brother's passport. I guess at mothercare, they filled in the form for him where as at CPW we need to fill in the form ourselves). The administrative fee as charge by Carphone Warehouse is about 40% of the total VAT. So, effectively, the refund amount is only 12%. I'm not sure if the admin fee is a fixed amount or if it is a percentage of the total VAT. Anyway, below is the detail: 

Product Total Price:£149.00 (£124.17 before VAT)
Total VAT:£24.83
Admin fee: ~£9.93
VAT to refund:£14.90

At the Heathrow Airport
With a valid student visa, the officer asked for a proof/letter from the university stating that my friend have finished the studies. There were two options in submitting the VAT refund form. The first option is to hand in the form to the officer for processing later and there was no need to queue. We decided to use the second option in order to get a cash refund. There were two lines for the cash refund. The shorter queue is for less than three receipts and the longer queue is for more than three.
My friend has two receipts with £14.90 amd £2 refunds. The £2 refund cannot be accepted as it is too little. For the £14.90 receipt, only £11.23 was refunded after subtracting the handling fee of £3.67. Once again, I didn't know if the handling fee is a fixed amount or a percentage of the total amount.
Even though, there was a notice on the wall stating that VAT refund for electronic items need to be done after security, my friend managed to get the refund before security.

VAT to refund: £14.90
Handling fee: £3.67
Cash refunded: £11.23

In conclusion, my friend was initially charged £24.83 for VAT (20%) and £11.23 was refunded. This is 9.05% VAT on the product price before VAT. Effetively, less than 50% of VAT amount was refunded.

First Light on Orion Nebula using SPC900nc LX Mod

Celestron C6 on Nexstar SLT Mount

Hyperstar Lens with Baader SkyGlow Filter

FL 290mm at f1.9

SPC900NC - LX/ Amp Off

10x4s with Dark frames

Stacked with DSS

11//11/2012 01:09 AM

Field of View (FoV) Calculator

http://www.12dstring.me.uk/fov.htm

Key in the telescope information and eyepiece/camera information. Chose the simulated object to observe.

USB Pin Layout

Red      Vcc
White   Data-
Green   Data+
Black   GND

Ref.

PL2303 USB to Serial Adapter Code 10 Cannot Start

Update 24/11/2012
It's still BSoD sometimes. Not the version of driver I guess.

Update 13/11/2012
Seems good so far. No BSoD yet.

Update 11/11/2012
My desktop computer seems to be crashing (BSoD) sometimes when using the SPC900nc/USB hub/Prolific serial usb COMBO. I'm not sure which one is causing the trouble. I switched the driver to this one,

USGlobalSat Prolific GPS AllinOne.
Driver Date: 10/27/2008
Driver Version: 3.3.2.105

---------------------------------------------------------------

Error: This device cannot start. (Code 10)

Solution: Install using vista driver.
Result: Will be recognised as 'This a PL-2303 XA / HXA chip' when checked using the chip checker.

Serial DB9 Pin Layout
Row of 5 (Pin 1 to 5)
2 - Rx
3 - Tx
4 - DTR (Exposure)
5 - GND

Row of 4 (Pin 6 to 9)
7 - RTS (Amp-off)

USB Pin Layout

Red      Vcc
White   Data-
Green   Data+
Black   GND

Wh to Ah Conversion

Power(W) = Current(A) * Voltage(V)
Wh = Ah * V

Telescope 12V Portable Battery Pack Anker Astro3 9V 5V

Anker Astro3
2 USB @ 5V 2A and DC @ 9V/12V 2A
10000mAh@5V
37Wh = 3.1Ah@12V

I have been using this battery pack for the Nexstar SLT mount with C6 OTA for about 3 months. It has 12V or 9V @2A (selectable one at a time) output unlike most if not all USB battery pack which only comes with 5V output. It is larger than a regular 5V USB battery pack but way more portable than acid lead battery.
The rated energy at 12V (37Wh) seems to be lower than 5V (50Wh). Assuming the battery is 5V, there could be energy loss when converting from 5V to 12V i.e. 75% efficiency. However, I don't know the actual battery rating as I haven't cracked open the battery pack yet.
It has 4 blue LED indicators to show the battery capacity. There are rather nice with your desktop but a bit distracting to the eye in the field at night. I need to shield the LEDs behind the mount.
The instruction manual for the mount states that it requires 12VDC@750mA. I guess that is the maximum current draw when slewing at maximum speed in both Alt/Az axes. When tracking, it should use less current as it is moving at slower speed.  Even at maximum current of 750mA, the battery pack should last for about 4 hours.
During an observation session, I typically only observe 2 or 3 objects in the sky. So, that is not a lot of slewing at maximum speed. Throughout the session, the mount is always in tracking mode for both axes. When viewing at very high magnification, I need to correct the tracking by slow slewing back and forth in order to bring the object into the centre of the eyepiece or camera. The battery usage is less than 50% after about 3 hours. Sometimes, during short session, I only used out one LED. So, there is plenty of juice left. 5 or 6 hours of tracking should be possible in a single charge. May be I should measure the current consumption during tracking and slewing for better estimation.
I've retrofitted a diy arduino motor focuser to the C6 OTA and later will add a nichrome dew heater as well. We'll see how the Anker battery pack performs with the two extra gadgets.

Update 25/11/12 : Nexstar SLT and Arduino Motor Focuser Current Measurements

Power(W) = Current(A) * Voltage(V)
Wh = Ah * V

Amazon Price History

http://camelcamelcamel.com/

Arduino Rotary Encoder

http://www.buxtronix.net/2011/10/rotary-encoders-done-properly.html
Implementation with and without external interrupt. Using two encoders is also possible.

Stepper Motor 28BYJ-48 5V

http://arduino.cc/forum/index.php/topic,71964.0.html
Gear ratio: (22X26X31X32)/(9X9X10X11) = 63.68395.    ( 283712/4455) 

Arduino Interrupt Software Debounce

Ref: http://www.dave-auld.net/index.php?option=com_content&view=article&id=107:arduino-interrupts&catid=53:arduino-input-output-basics&Itemid=107

int pbIn = 0;                  // Interrupt 0 is on DIGITAL PIN 2!

02.int ledOut = 4;                // The output LED pin

03.volatile int state = LOW;      // The input state toggle

04. 

05.void setup()

06.{               

07.// Set up the digital pin 2 to an Interrupt and Pin 4 to an Output

08.pinMode(ledOut, OUTPUT);

09. 

10.//Attach the interrupt to the input pin and monitor for ANY Change

11.attachInterrupt(pbIn, stateChange, CHANGE);

12.}

13. 

14.void loop()                    

15.{

16.//Simulate a long running process or complex task

17.for (int i = 0; i < 100; i++)

18.{

19.// do nothing but waste some time

20.delay(10);

21.}

22.}

23. 

24.void stateChange()

25.{

26.state = !state;

27.digitalWrite(ledOut, state); 

28.}