經上週開光及前晚調試完成後，昨日是第一次把0.8米反射運到星河科研社於青協大美督的基地活動，為四十多位來自不同學校的香港資優教育學苑學生進行為期半年的天文觀測培訓。基地靠海，視寧度可以十分理想，是我投入天文愛好多年來所罕見。昨晚開始時月球仰角只有四十多度，已能用 TeleVue Ethos 8 mm 目鏡以350 倍觀察，然後再轉用 TMB Supermonocentric 5 mm 目鏡推上 550 倍，因為集光力及解像度充足，酒海邊沿的西奧菲勒斯 (Theophilus) 坑的環形山峰呈現如刀峰一樣的對比度。大氣未至於完全靜止，但日落後才一個多小時，這種視寧度也是罕見。

之後指往土星，仰角只有三十度，視寧度略受影響，但近乎扁平的光環，其陰影如刀割一樣橫切土星本體，那種對比度，不是我當年那單鏡筒都要三十萬元的 TMB 203 APO 折射鏡能比。我也曾擁有 TMB 254 APO，但更像我在深圳西涌天文台，安裝好造價數百萬元的TMB 304 APO 雙筒後目視土星的情景。土星兩邊共五顆衛星一目了然，第六顆距離較遠，不在像場內。要承認，至今用的望遠鏡經驗只看過五顆土星衛星，但頗肯定只要大氣透明度合理，加上星圖確認，可以看到十顆以上。

之後便是獵戶座大星雲，Ethos 21、13、8 一級級對上去，中央的四合星輕易而舉，旁邊還有 10 等多的 E 及 F 星，也明顯比 TMB 203 APO 輕鬆得多（我 2010 年也在高美古用當時全國最大 2.4 米 RC 望遠鏡目視這四合星）。可恨昨天沒時間重看日前在城門河畔貌似看到但被厚雲層干擾的天狼星伴星。一如日前的情況，星雲綠色很明顯，更是第一次明確看到這星雲的紅色(之前試過在理想環境下用40公分Dob隠約看過)。更特別的是現在的綠不像過往從小望遠鏡看到的綠(少年時用10公分反射在家裡陽台也能看到)，而是摻雜了紅的混色，即從中央四合星位置的青綠，往外為粉紅，再往外為褐紅的過渡。剛好手上沒有目視光害濾鏡及合適接環，手持Antlia RGB Triband Ultra濾鏡在彗差鏡前試試，星雲的絲狀雲氣湧現，對比度大幅提升。二十年前我在德國來回測試 Starmaster 24 吋反射及 TMB 254 APO，很期待到夏天時再看同一堆深空天體，特別是 M57 戒指及 M27 啞鈴星雲那種層次豐富的雲氣，還有戒指中央的原白矮星。

然後天色開始轉差，但仍爭取時間指向木星。大紅斑剛好在正面，就算在雲層後，大紅斑的色彩飽和度也遠勝在場我天文台內的Celestron EdgeHD 14。同時以昨晚情況來看，觀察木星面那些像鯊魚鰭的雲彩 (festoon)、白斑 (oval) 及黑斑 (barge) 會輕鬆得多，特別是木衛三的圓面很清晰。天氣好一點時，看衛星表面地貌(我用203APO拍過)也肯定比之前用 TMB 203 APO 及配有 Mike Lockwood 45公分主鏡的 Obsession 18UC舒服得多。

其實這段時間忙得要命，星河科研社一個週五六日可以有五至八場活動，加上昨日有數十位學生要進行培訓並評審第一階段科學報告，但也堅持趁天氣轉壞及進入雨季前把鏡運入基地測試。主要是要及早完成電腦化台架的指向及追蹤調校，檢測精確調整光軸並調好彗差修正鏡後焦點的光學表現，把一齊要天氣配合的調試完成，確定這鏡能實現預期中的表現。結果十分美滿，這鏡先天精度極高，是足厚度主鏡及科研級的RMS 1/30波長精度，而後天的機械裝配及調校，再加上高視寧度環境，讓目視表現超越我過往任何一台望遠鏡，也打破了一直以來的觀念即f/3短焦反射不可能是高水平行星月面鏡，而且也初步測試了行星拍攝的可能性。可以說我已重燃目視的興趣，收起多年的、總值十萬元的兩套全焦段 TMB Supermonocentric / Aspheric Ortho 目鏡可以出山了，也會看看這鏡的月面行星攝影會比自己的 Celestron EdgeHD 14 好多少。當然也跟學生提過，他們很幸褔，初接觸天文便能用全港最大的0.8米反射鏡觀星，日後也能繼續用來研習天文。

隨後會在這裡繼續分享更多測試報告。

After completing final collimation and optical alignment during the pre‑commissioning night last week, the 0.8 m reflector was transported yesterday to the Galaxy Research Society’s observing base at HKFYG Tai Mei Tuk, for the first official activity session. There, more than forty students from the Hong Kong Academy for Gifted Education (HKAGE) participated in a six‑month astronomy training program.　

The site is located by the sea, with often remarkably stable seeing, the best I have encountered in my years of visual observing. At the beginning of last night’s session, the Moon stood about 40° above the horizon. Using a TeleVue Ethos 8 mm eyepiece (350×) and later switching to a TMB Supermonocentric 5 mm (550×), the telescope’s tremendous light‑gathering power and resolution revealed the knife‑edged contrast of the Theophilus crater peaks on edge of Mare Nectaris. Though the atmosphere was not perfectly still, such steadiness only an hour after sunset was extraordinary.

Next came Saturn, at an elevation of just over 30°, slightly affected by seeing, yet the almost flattened rings cast razor‑sharp shadows across the planet, a level of contrast surpassing even my former TMB 203 APO refractor, which cost HKD 300,000 for the optical tube alone. The view recalled my earlier sight through the TMB 304 APO binoculars at Xichong Observatory. Five Saturn moons were directly visible; a sixth lay beyond the field of view. Under better transparency and with star‑chart assist, I’m confident that, ten or more moons can be detected.

Then we turned to the Orion Nebula (M42). Using the Ethos 21 mm, 13 mm, and 8 mm eyepieces in succession, the Trapezium’s four main stars and the fainter E and F components (>10 mag) were clearly seen, far easier than through the former TMB 203 APO. (In 2010, I also visually observed the Trapezium through China’s then‑largest 2.4 m RC telescope at Gaomeigu Observatory.) Regrettably, I didn’t have time last night to revisit Sirius B, the faint companion of Sirius, which I seemed to glimpse the other day from the Shing Mun River before it was obscured by thick clouds. As on previous nights, the green hue of the Orion Nebula was obvious, but this time I could clearly perceive its red component, something I had only barely suspected years ago with a 40 cm Dobsonian under ideal conditions. What struck me most was that the green now appeared different from the pure green seen through smaller telescopes, back in my youth, even a 10 cm reflector on the balcony could show that color. Now, instead, the tone was a blend of green and red, shifting gradually outward from the Trapezium’s aqua‑green core to a soft pink ring, and finally to a reddish‑brown outer transition. I happened not to have a visual light‑pollution filter or the proper adapter at hand, but by holding an Antlia RGB Triband Ultra filter by hand in front of the coma corrector, the nebula’s filamentary structure suddenly surged into view, and the contrast improved dramatically. Two decades ago, while alternating between a Starmaster 24‑inch Dobsonian and a TMB 254 APO in Germany, I could only imagine this level of nuance. Now I look forward to the coming summer to observe the same set of deep‑sky objects, especially the M57 Ring Nebula and M27 Dumbbell Nebula with their richly layered gas, and to catch sight of the pre-white‑dwarf at the heart of M57.

As the sky began to haze, I still aimed at Jupiter. The Great Red Spot was squarely in view, and even through intermittent thin cloud its color saturation surpassed that of our Celestron EdgeHD 14 in the observatory. Jovian details, festoon, white ovals, and dark barges, can be rendered with ease. Ganymede’s disk appeared clean and well defined; under steadier air, its surface shading would certainly be more distinct than in the TMB 203APO or the Obsession 18UC with a Mike Lockwood primary. Which I imaged before with the TMB 203APO

Despite an extremely tight schedule (the Galaxy Scientific Group often runs 5 to 8 outreach programs per weekend, and yesterday dozens of students were being assessed on their first‑phase science reports), I insisted on bringing the telescope out before the rainy season to complete field testing. The goal was to tune up the computerized mount pointing and tracking, verify precise collimation and the coma‑correction backfocus, all of which performed beautifully. The results were highly satisfying. This telescope’s intrinsic optical precision is exceptional, its full‑thickness primary mirror achieves a research‑grade RMS accuracy of 1/30 wave. Combined with accurate mechanical assembly, careful alignment, and excellent seeing conditions, its visual performance has surpassed that of any telescope I have previously owned.

It also challenges the long‑held belief that a fast f/3 reflector cannot deliver high‑quality planetary and lunar views, and the initial trials have even demonstrated promising potential for planetary imaging. It is time to "bring out of retirement” my long‑stored, full‑focal‑range TMB Supermonocentric and Aspheric Ortho eyepieces worth over HKD 100,000, and see how this mirror’s lunar and planetary imaging compares to the Celestron EdgeHD 14. Of course, I also mentioned to the students how fortunate they were to begin their journey in astronomy with the opportunity to observe through Hong Kong’s largest 0.8 m reflector telescope, and that they will have the chance to continue using it in their future astronomical studies.

Further test results and observation reports will be shared here in due course.