Lunar Crescent Workshop (Thierry Legault)

Lunar Crescent Workshop Thierry Legault Surabaya, Indonesia April 26-28 2014 Edition 2

Lunar crescent workshop - Thierry Legault 2014

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Agenda: day 1 • The Moon and the crescent: – – – –

Basic notions Using Stellarium planetarium program The lunar phases Seeing and imaging the crescent

• The GM8 mount and the Gemini2 system: – assembly and installation – polar alignment

• Outdoor practice with GM8 and Gemini2 Lunar crescent workshop - Thierry Legault 2014

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Agenda: day 2 • Imaging: – – – – – – –

Setting the telescope Making and using the solar filter and the sunshield Adjusting the solar and lunar rates Pointing the Sun and the Moon Checking the celestial coordinates Using the video camera Processing the video sequences

• Outdoor practice with GM8 (optional) Lunar crescent workshop - Thierry Legault 2014

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Agenda: day 3 • Outdoor practice of lunar video acquisition • Processing the video sequences • Workshop feedback/wrap-up

Lunar crescent workshop - Thierry Legault 2014

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Basic notions: angles in astronomy • An angle represents the apparent size of an object or the apparent distance between two objects • Moon = Sun = ½° diameter • The angle between the Moon and the Sun is called the Elongation

Lunar crescent workshop - Thierry Legault 2014

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Basic notions: the Universal Time (UTC) • UTC = Universal Time Coordinated • Reference for astronomical and scientific/technical world

• Formerly: Greenwich Mean Time (GMT) • West Indonesia = UTC + 7h • Central Indonesia = UTC + 8h • East Indonesia = UTC + 9h

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Startup Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Choosing location Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Choosing location Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Choosing date/time Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Choosing date/time Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Choosing speed Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Finding object Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: using Stellarium

Finding object Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the lunar phases

(source: http://upload.wikimedia.org/wikipedia/commons/4/46/Moon_phases_en.jpg) Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the lunar phases • The phase is the fraction of the lunar disk illuminated by the Sun as seen from Earth: • Full Moon (all night) = 100% • First/Last Quarter (evening/morning) = 50% • Visible Crescent (sunrise/sunset) = a few percent • New Moon (daytime) = less than 1% • Total solar eclipse = 0% • Average time between two Full Moon or two New Moon: 29d 12h 44m 2.9s • New Moon can happen at any hour (day or night), depending on the date

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the lunar orbit

Inclination of lunar orbit ~ 5째 with respect to ecliptic (Earth orbit plane) Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the conjunction • Conjunction (New Moon) happens when: lunar ecliptic longitude = solar ecliptic longitude • Topocentric conjunction: as seen from a specific place on Earth • Geocentric conjunction: as seen from the center of the Earth • Topocentric and geocentric times may differ by up to 4 hours, because of the parallax • At conjunction, the Elongation (EL) can take any value between -5° and +5° • When EL is less than ½°, there is a solar eclipse (partial or total) • The Age of the Moon is the time passed after conjunction • The EL increases with the Age, at an average of 12°/day • Crescent brightness and thickness increase with EL • Solar glare decrease with EL Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the elongation in Stellarium

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: visibility of the first thin crescent

Conjunction Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: visibility of the first thin crescent • Visibility with naked eye or binoculars needs: • a dark sky => after sunset • the Moon a few degrees above the horizon

• This implies a lower limit to EL => 12 hours minimum after conjunction • Moonset (Moon at horizon) is invisible because of atmospheric extinction (absorption of light)

• Transparency of the atmosphere is very important: • no clouds • no fog, smoke, pollution, humidity => blue sky even close to horizon • moutain sites are often better (if no high clouds)

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the conjunction crescent (1/2) • EL is always less than 5° • The Moon and the Sun set almost at the same moment • The conjunction crescent is detectable in daylight only with photography • Visibility with the eye (naked or aided with telescope) is physically impossible • Daylight photography needs infrared filter (and monochrome sensor, sensitive to infreared) to decrease the brightness of the blue sky

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: the conjunction crescent (2/2) • The EL must not be too small • World record so far: EL = 4.2° • Transparency of the atmosphere is critical: • no clouds • no fog, smoke, pollution, humidity => blue sky even close to the horizon • moutain sites are often better (if no high clouds)

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: topocentric conjunction time

Find the time when Ecliptic Topocentric longitude of Moon and Sun are closest Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: topocentric conjunction time

Find the time when Ecliptic Topocentric longitude of Moon and Sun are closest Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: topocentric conjunction time

Find the time when Ecliptic Topocentric longitude of Moon and Sun are closest Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: topocentric conjunction time

Find the time when Ecliptic Topocentric longitude of Moon and Sun are closest Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: visibility charts

http://www.icoproject.org/ http://www.staff.science.uu.nl/~gent0113/islam/islam_lunvis.htm

Charts are approximations based on past experience and lunar position calculations

Lunar crescent workshop - Thierry Legault 2014

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The Moon and the crescent: visibility charts

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The Moon and the crescent: visibility charts

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The Moon and the crescent: visibility charts

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The Moon and the crescent: visibility charts

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The GM8 mount: assembly and installation

Deploy the tripod legs Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Do not install the tripod on loose or unstable ground where the tripod can sink or slide (sand, mud, gravel‌)

Extend the tripod legs Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Install the mount on the tripod and tighten the 3 screws Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: the axis of the mount

Movement axis: - RA = Right Ascension - DEC = Declination (δ)

Polar alignment axis: - AZ = Azimuth - LAT = Latitude

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: the equatorial coordinates

RA is expressed in hour/min/sec 05h 34m 56s Range: 0 to 23h 59m 59s

DEC is expressed in degrees/min/sec 45° 12’ 09’’ Range : -90° to +90°

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Direct the polar axis leg to South for the southern hemisphere (North for northern hem.) with the help of the compass Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Bad

Good

Adjust the tripod legs for horizontality (2 bubble levels) Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Pre-adjust the latitude of the observation site with the LAT knob and scale Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Use a bubble level and a triangle (cut according to the latitude) to adjust the latitude.

If necessary, use the polar axis leg extension Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

The latitude triangle Surabaya example: latitude = 7.25째; tan(7.25째) = 0.127; 200*0.127 = 25.4 mm Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Screw the counterweight bar and install the counterweight Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Install the telescope (ÂŤ CWD Âť position = CounterWeight Down) Lunar crescent workshop - Thierry Legault 2014

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The telescope: components

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Unscrew RA knob, adjust counterweight balance.

Check that the counterweight does not touch the tripod leg.

Put the mount in ÂŤ CWD Âť position. Screw RA and DEC knobs.

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Install the control panel.

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Screw the RA motor.

Plug the RA cord between the control panel and the RA motor Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Screw the DEC motor.

Plug the DEC cord between the control panel and the DEC motor Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Plug the hand controller in ÂŤ Graphic HC Âť.

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Plug the GPS in ÂŤ Serial port 1 Âť Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Plug the 12V power supply Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: The Gemini 2 system

Complete user manual:

http://www.gemini-2.com/

Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: initialization

Switch on the mount while in ÂŤ CWD Âť position Let the star display pass Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: initialization

Press « cold start », « Back » Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: initialization

Press ÂŤ Back Âť again to go to the Main Menu page Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: site check

From Main Menu page, press « Menu », « Site » Press « Query GPS » when outside and check coordinates and Timezone Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: time check

From Main Menu page, press « Menu », « Time » Check (or change) Timezone, Civil date and Civil Time, press « Set » Lunar crescent workshop - Thierry Legault 2014

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The Gemini 2: mount parking

From Main Menu page, press « Menu », « Park », « Park at CWD Position » Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: assembly and installation

Align the finder on a distant target (terrestrial at several km, or celestial) Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment (southern hemi.)

• Polar alignment consists in physically aligning the polar axis of the mount with the polar axis of the Earth, so that: • all stars can be perfectly tracked with the rotation of the RA axis of the mount at sidereal rate (one turn in 23h 56m 4.09s) • The « GOTO » system of the mount can point any celestial object with sufficient accuracy • Poor polar alignment leads to a drift of objects in the field of view (eyepiece or camera) • For crescent imaging, polar alignment shall be better than 3 arc minutes (1/20 °)

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: setting the sidereal tracking rate

From Main Menu page, press « Menu », « Track », « Sidereal » Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

Point a bright star at North and altitude between 30째 and 60째 (halfway between horizon and zenith).

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

Align the axis of the crosshair eyepiece with the axis of the mount Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

If the star drifts up, use the AZ knob to rotate the mount counterclockwise If the star drifts down, use the AZ knob to rotate the mount clockwise Repeat the corrections until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

If the star drifts up, use the AZ knob to rotate the mount counterclockwise If the star drifts down, use the AZ knob to rotate the mount clockwise Repeat the corrections until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

Point a bright star at East and low altitude (15 to 25째) Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

If the star drifts left, use the Latitude knob to pull down the polar axis If the star drifts right, use the Latitude knob to pull up the polar axis Repeat the correction until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

If the star drifts left, use the Latitude knob to pull down the polar axis If the star drifts right, use the Latitude knob to pull up the polar axis Repeat the correction until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment southern hemi.

Go back to the previous star and check the drift, etc.

Make adjustments until there is no visible drift on both stars during at least 3 min Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

Point a bright star at South and altitude between 30째 and 60째 (halfway between horizon and zenith).

Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

Align the axis of the crosshair eyepiece with the axis of the mount Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

If the star drifts up, use the AZ knob to rotate the mount clockwise If the star drifts down, use the AZ knob to rotate the mount counterclockwise Repeat the corrections until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

If the star drifts up, use the AZ knob to rotate the mount clockwise If the star drifts down, use the AZ knob to rotate the mount counterclockwise Repeat the corrections until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

Point a bright star at East and low altitude (15 to 25째) Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

If the star drifts left, use the Latitude knob to pull up the polar axis If the star drifts right, use the Latitude knob to pull down the polar axis Repeat the correction until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

If the star drifts left, use the Latitude knob to pull up the polar axis If the star drifts right, use the Latitude knob to pull down the polar axis Repeat the correction until there is no visible drift during at least 3 minutes Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment northern hemi.

Go back to the previous star and check the drift, etc.

Make adjustments until there is no visible drift on both stars during at least 3 min Lunar crescent workshop - Thierry Legault 2014

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The GM8 mount: polar alignment

CAUTION: If the mount or one leg of the tripod is moved, even by 1 mm, Alignment is LOST

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Imaging: setting the telescope

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Imaging: making the solar filter

Use the instruction sheet provided with the filter: http://www.baader-planetarium.com/sofifolie/bauanleitung_e.htm Internal diameter of housing matches the external diameter of the end of telescope Lunar crescent workshop - Thierry Legault 2014

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Imaging: making the sun shield

Use currugated cardboard roll, width at least 1.20 m Lunar crescent workshop - Thierry Legault 2014

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Imaging: making the sun shield

Cut cardboard at least 1.20m long, make a tube, insert it over the telescope shield and fix the ends with cord Lunar crescent workshop - Thierry Legault 2014

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Imaging: pointing the Sun

From Main Menu page, press « GOTO », « Solar system », « Sun » Lunar crescent workshop - Thierry Legault 2014

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Imaging: setting the solar tracking rate

From Main Menu page, press « Menu », « Track », « Solar » Lunar crescent workshop - Thierry Legault 2014

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Imaging: synchronizing on the Sun

From Main Menu page, press « Menu », « Align », « Synchronize » The display comes back to Main Menu page saying: Sync Sun Lunar crescent workshop - Thierry Legault 2014

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Imaging: pointing the Moon

From Main Menu page, press « GOTO », « Solar system », « Moon » Lunar crescent workshop - Thierry Legault 2014

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Imaging: calculating the lunar tracking rate (1/3)

Note the RA/DE (of date) lunar coordinates in Stellarium, 1 hour before and 1 hour after the imaging time (here: 2:46:25) Lunar crescent workshop - Thierry Legault 2014

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Imaging: calculating the lunar tracking rate (2/3)

Input them in the lunar rate calculation Excel sheet Lunar crescent workshop - Thierry Legault 2014

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Imaging: calculating the lunar tracking rate (3/3)

Press Menu, Track, User Define.

Input the calculated differences Delta RA and Delta DEC in the User Define Rate page of Gemini2, with timespan = 2:00:00, then press ÂŤ Set Âť Recalculate every 1 hour or so Lunar crescent workshop - Thierry Legault 2014

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Imaging: setting the lunar tracking rate

From Main Menu page, press « Menu », « Track », « Comet/User Defined » Do NOT use « Lunar » Lunar crescent workshop - Thierry Legault 2014

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Imaging: checking the lunar/solar coordinates

Compare Main Menu RA/DEC coordinates to RA/DE (of date) in Stellarium Difference must be less than 1m / 15’ Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Pulg the camera to the computer and launch iCap software Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

View useful toolbars Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

View histogram Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Choose record directory and video filename with time stamp Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Choose frame rate as maximum possible (30) Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Choose format AVI and Codec RGB24 (uncompressed) Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Choose video sequence duration: click on Toggle Recording Control Dialog, then on the little clock and input duration Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Let gain at 0.00 dB, manual (no Auto) Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Adjust exposure time so that histogram maximum is 2/3 to 3/4 of the range Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Bad: underexposed

Bad: overexposed

Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

Launch video sequence acquisition with ÂŤ start recording Âť button Lunar crescent workshop - Thierry Legault 2014

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Imaging: video acquisition

View elapsed time and number of frames with Record Video File dialog box Lunar crescent workshop - Thierry Legault 2014

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Video processing step 1

Launch VirtualDub and open the AVI video file to process Lunar crescent workshop - Thierry Legault 2014

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Video processing step 2

Export to a BMP image sequence Name: i Minimum number of digits: 1 Lunar crescent workshop - Thierry Legault 2014

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Video processing step 3

Export to a BMP image sequence and note the number of last frame (here 887), Click OK and let the process finish (a few minutes needed) Lunar crescent workshop - Thierry Legault 2014

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Video processing step 4

Launch Iris and check the presence of the Command window and the Threshold window Lunar crescent workshop - Thierry Legault 2014

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Video processing

Settings of Iris (to do once): set the working path = video directory and file type = FIT Lunar crescent workshop - Thierry Legault 2014

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Video processing step 5

Convertion: in the command window, type convertbmp24 i i N Press enter and let the process finish (a few minutes needed) (N is the number of the last bmp file) Lunar crescent workshop - Thierry Legault 2014

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Video processing step 6

Stacking: in the command window, type add_norm i N Press enter and let the process finish (a few minutes needed) Lunar crescent workshop - Thierry Legault 2014

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Video processing step 7

Background removal: click Processing, Wavelet Lunar crescent workshop - Thierry Legault 2014

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Video processing step 8

Background removal: slide Remain to 0 (left) and press OK Lunar crescent workshop - Thierry Legault 2014

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Video processing step 9

Background removal: in the Command window, type offset 16000 Press Enter Slide the high threshold to the right (32767) Lunar crescent workshop - Thierry Legault 2014

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Video processing step 10

Slide little by little the high threshold to the left and the low threshold to the right to increase contrast Lunar crescent workshop - Thierry Legault 2014

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Video processing step 11

Save the image in JPEG: click File then Save Choose JPEG as file type and give a name Lunar crescent workshop - Thierry Legault 2014

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Imaging checklist 1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

If necessary, switch on the mount (CWD position) Install the solar filter Point the Sun with GOTO Focus the Sun through the eyepiece Connect the video camera to the computer and launch iCap software Adjust video camera parameters for good visibility of sunspots Focus carefully on sunspots through the video image Center the Sun in the camera frame with the hand controller buttons ÂŤ Synchronize Âť the Gemini2 on the Sun check solar RA/DEC coordinates Point the Moon with GOTO and check RA/DEC coordinates Remove the solar filter Calculate and set the lunar tracking rate Adjust video camera parameters for lunar acquisition Take video sequences of 1 minute long Every hour or so, check focus and re-synchronize on the Sun (step 2 and more)

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Possible mistakes and problems Problem

Symptom

Poor polar alignment

Objects drift in sensor/eyepiece

Wrong tracking rate

Objects drift in sensor/eyepiece

Wrong time or site

Wrong direction when use of GOTO

Poor focus

Objects fuzzy (or not visible) in sensor/eyepiece

Solar filter not in place for Sun

Danger for sensor or your eyes!!!!!!!!!!!!!!!!!!!!!!!

Solar filter in place for Moon

Nothing visible (black image)

Mount axis not tighten

Wrong direction when use of GOTO

Mount axis moved manually after polar alignment/synchro

Wrong direction when use of GOTO

Tripod moved or az/lat knobs touched after polar alignment

Polar alignment lost

Message ÂŤ motor stalled Âť

Motor disconnected Lunar crescent workshop - Thierry Legault 2014

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The 3 keys for success Train Train Train

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Notes

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Notes

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Notes

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Notes

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