Faint Comet Found

Just as I was settling down and thinking about making my morning cup of tea, I thought I’d check the eastern sky one last time (see my earlier post about cloud cover on the wrong half of the sky). Surprise!  The clouds disappeared, probably due to the wind advisory we’re still under.  I could barely see the star Spica just breaking through the bare limbs of my neighbor’s trees.

I went back inside and grabbed my binoculars.  I then headed to one of my east-facing second floor bedrooms.  Thanks to my kids, the window in the south room has no screen so I can open it and have a clear view above my neighbor’s rooftops.

Continue reading “Faint Comet Found”

Can’t See Comet for the Clouds

I work up at 4:11 a.m. (Central Time) this morning. It’s a Sunday. Why am I up so early? I have no idea.

Since I was up early, I checked my Sky Safari app on my smartphone to see when Comet Ison would rise. I was in luck. It was scheduled to rise at 4:22, a few minutes before the star Spica.

Continue reading “Can’t See Comet for the Clouds”

Venus Dives Past Saturn

Twelve degrees Fahrenheit this morning as I setup the tripod and camera for the third pre-dawn photo shoot of Saturn and Venus.  Completely calm, unlike yesterday morning, so no jiggles to the camera, beyond my fumbling numb fingers.  I opted for longer exposures (three or four seconds), so I ended up with some trails, especially when using the telephoto lens.  Otherwise, much the same as before, with the exception of the planetary dance partners.

SaturnVenusMercury3secExp18mmWithLabels
Venus slipping below Saturn pre-dawn Tuesday 11/27/2012 (click image for rest of album)

I don’t plan on repeating this for a fourth time tomorrow morning, but I do plan on trying to capture the full moon as it approaches Jupiter tomorrow night.  There also happens to be a penumbral lunar eclipse occurring Wednesday evening.

Wednesday, November 28
Full Moon arrives at 9:46 a.m. EST. It appears against the background stars of Taurus the Bull before dawn this morning, approximately midway between the Pleiades and Hyades star clusters and below brilliant Jupiter. (The Moon will slide within 1° of the planet after sunset tonight.) But the Moon has a lot more going for it today. First, it passes through the outer part of Earth’s shadow. This penumbral lunar eclipse will slightly darken the Moon’s northern half. People in much of North America can see the eclipse’s early stages, which begin at 7:15 a.m. EST. (Those in Australia, eastern Asia, and the Pacific islands have the best views of the event.) Second, this Full Moon is the smallest (29.4′ in diameter) of 2012. Our satellite’s relatively diminutive size arises because it reaches the farthest point in its orbit around Earth at 2:37 p.m. EST today, when it lies 252,501 miles (406,362 kilometers) from Earth’s center. (Astronomy.com ‘The Sky This Week – November 23 – December 2, 2012’)

Begining of the End

I learned last night at the November general meeting of the Astronomical Society of Kansas City that we have just fifty days (forty-nine as I write this blog) until the end of a Mayan age (the 13th Bak’tun).  More commonly known to us as the Winter Solstice on December 21, 2012 (12/21/12 or 21/12/12 depending on your longitude).  I had a lot on my mind as I drifted off to sleep last night,  but when I woke to clear skies and a newly risen Venus blinking at me through the bare branches of trees along my eastern horizon, I shook off the last vestiges of ancient doom and gloom and braved the brisk late fall pre-dawn environs with my tripod and camera.

Armed with new tips and techniques garnered from Tom Martinez’s astrophotography presentation during the club’s Astro 101 session, I attempted a long exposure (ten seconds long) of the Big Dipper using my normal lens:

BigDipper10secExp

I was gratified to discover that my camera can take even longer exposures without the necessity of a handheld remote. Not that I don’t plan to purchase a remote for it soon though.

I didn’t attempt to capture Canis Major or Orion in a long exposure since I would have been shooting west over the well-lit parking lot of City Hall.  Instead, I turned my camera towards the southeast and bright shining Venus and the slightly dimmer Saturn.

VenusSaturnMercurySpicaArcturusWideAngleShot3secExpWithLabels
Wide angle shot of Venus, Saturn and Mercury (click image for rest of album)

I knew Mercury had risen shortly after six o’clock, but I couldn’t see it clearly until about a quarter after.

MercuryAlphaLibrae4secExp
Mercury & Alpha Librae in a four second long exposure.

Later, I accidentally captured not only Mercury, but a passing plane, as it took off from KCI (northeast of my location).

MercuryAlphaLibrae1secExpAWBwithPlaneStreak
Passing Plane (the streak) approaching Mercury

When I got back to my laptop and downloaded the photos, I also double-checked and compared them to the alignment at the time they were taken using the Star Dome Plus java applet at Astronomy.com:
SoutheasternHorizon45degSun25Nov2012-0615A short successful photo shoot this morning.  I didn’t hang around for the sunrise, since I judged it wouldn’t be as pretty as the one I captured Saturday morning.

VenusSaturnMercuryAlphaLibrae3secExpAWB
Venus-Saturn-Mercury Line-up Sunday morning 11/25/2012

Weather permitting, I’ll be repeating this activity for the next two or three mornings. I’m excited to see Venus and Saturn pass each other in the night (or very early morning).

And next week I’m going to wish I was visiting Egypt to witness a once in 2,737  years event involving these same three planets and the Great Pyramids at Giza.

Return of Saturn

The new moon occurs tomorrow just eight minute’s past four o’clock in the afternoon.  I reviewed the sun rise and moon rise times for today, tomorrow and the next day as compared to the time the new moon happens.  And, once again, the ‘holy grail’ of observing a moon less than one day from dying or one day new-born eludes me.  Tomorrow morning, on the 13th of November, 2012, moon rise occurs at 6:41 a.m. Central, just twenty minutes before the sun rises.  If that wasn’t ‘bad’ enough, I’ll be driving the van for the Tuesday commute to work at that time.  My final rider pickup occurs at that time, so I may be able to take a couple of minutes with my binoculars to see if I can see the almost dead moon about eight hours before it is reborn as the new moon.  I don’t have high hopes though, as twenty minutes before sun rise is quite bright and the eastern horizon will be hazy unless I’m extremely lucky. And the chance of catching any sign of the extremely young moon (less than an hour old by sun set tomorrow night) is even slimmer than the crescent moon would appear at that time. 

Countertop & Backsplash Refinishing
Countertop & Backsplash Refinishing (click photo for rest of album)

I woke up knowing the temperatures had plummeted to the lower 20s overnight, leaving the sky crystal clear and killing the wind we’ve had for the past week.  Since my kitchen is completely unusable for the next week or so, I decided to pack up the van for the Monday commute, start it up (since frost completely covered all the windows) and gather up my camera equipment for an pre-dawn frigid photo shoot of the nearly dead moon.

NineteenMinsAfterMoonrise12Nov2012I drove the still cold and nearly empty van up the hill to the dead-end in front of City Hall.  I left the van running to continue the process of thawing out the windows and doors while I took the tripod and camera a few feet back up the hill to the east side lawn of City Hall.  I could barely see the new risen moon through the leafless trees lining the south and southeastern horizon.  I found a spot where the moon just clear the tree limbs and setup the camera equipment.  I took my first photo at 5:47 a.m., about nineteen minutes after the moon rose (at 5:28 a.m.).  I tried various settings and exposures, while trying to keep my hands warm and not shake the camera too much.  I took several unsatisfactory photos for about ten minutes and then returned to the van.  I needed to fill up the gas tank and get something warm to drink before heading south to pickup my first setup of riders.  My local rider had the day off because he’s a federal employee and today is the day set aside to observe and honor our veterans.

ThreePercentIlluminated0610am12Nov2012
Illuminted 3% at 6:10 a.m. Central Mon 12 Nov 2012

After filling up the van, I drove back up the hill so I could cross Main Street using the light between City Hall and the Library and just happened to look east again. I noticed the colors caused by twilight and pulled into the Library’s parking lot for a second photo shoot.  I quickly reset up the camera and took another ten minutes worth of photos before continuing on to Scooters for a warm mocha and a caramel apple scone. 

VenusSpicaSaturnWaningMoon0712am12Nov2012labeled
Venus, Saturn, Spica and the Waning Moon

I downloaded the photos from the camera and reviewed them. I threw away most of the first photo shoot because I forget to set the two second delay timer and most of them were blurry. I logged into my Astronomy.com account and downloaded the sky dome for the east-southeastern horizon to confirm and label the objects photographed above.

EastSoutheastHorizon0711am12Nov2012

I had completely forgotten that Saturn had finally come out from behind the sun to become visible once again in the early morning.  In fact, Saturn rose just nine minutes after the moon did, although my camera did not capture it in my first photo shoot, probably because it was hiding behind some tree limbs.

I also photographed the Big Dipper, Orion, Canis Major and the Pleiades, but decided not to share the photos with anyone yet.  Because I didn’t change from my telephoto lens to my normal one, I did not get all the stars in the handle of the Big Dipper nor did I capture all of the stars in Orion. 

I’ll probably miss this weekend’s meteor shower, as I will be otherwise occupied during the day and not in a location that will provided dark enough skies to properly observe a shower.   A solar eclipse occurs tomorrow, but only for those excessively lucky people who live in the South Pacific.  For more of what’s up this week, visit Astronomy’s the Sky this Week website.

Astronomy Plus Geometery

I put an appointment on my calendar earlier this week with an alert to remind me to go chasing planets after sunset on Tuesday evening.  I make sure to check Astronomy and Sky & Telescope magazines’ websites for their ‘The Sky This Week’ observing articles and place the interesting (and observable from my location) items on my calendar.  Here’s the paragraph for Tuesday evening from Astronomy’s web site

Tuesday, August 21 – Our trio of bright evening objects — Saturn, Mars, and Spica — forms a pretty equilateral triangle (5° on a side) in the southwestern sky after sunset. But the highlight of the scene tonight is a gorgeous crescent Moon that hangs just 4° below Mars. Binoculars provide the best view of this celestial gathering. Look closely and you’ll notice the objects’ different colors. The Moon’s color depends largely on conditions in Earth’s atmosphere and could be anywhere from white (under a dry, haze-free sky) to yellow or even slightly orange. Sunlight reflecting off Saturn’s clouds has a golden glow while Mars’ ruddy deserts cast an orange hue. Blue-white Spica generates its own light from a scorching surface nearly four times hotter than the Sun’s.

∞ ∞ ∞

Terry and Sean had retreated to the band room for rehearsal and I sat slogging my way through the 49th Parallel, a British WWII film released in the United States under the title The Invaders.  I recorded it a couple of weeks ago off the TCM channel.  It drags and I still haven’t finished it.  So when my phone buzzed with the text message alert, I jumped, literally, at the chance to stop watching the film and start looking up at the sky. 

I took my camera gear and got in the van.  I couldn’t take the Bonneville because Sean’s car happened to be parked in front of the garage.  I didn’t mind taking the van; it’s what I drive every weekday anyway.  I left the house at 8:20, about fifteen minutes after sunset, so the western sky still shown with twilight.  I could clearly see the bright waxing crescent moon, but could not yet see Saturn, Mars or Spica.  I drove west and southwest from Lansing, trying to find a spot clear of trees on top of a hill to setup the camera.

MarsSaturnSpicaWaxingCrescentMoon21Aug2012-2115I ended up driving almost an hour all over the middle of Leavenworth County and even through the small unincorporated town of Jarblo.  I never did find a satisfactory location.  I finally stopped in the parking lot of the High Prairie Church at the corner of 187th street and the end of Eisenhower Road.  The church had blazing bright lights illuminating their building, but I parked far away at the north end of the parking lot and used the van as a shield.  I took several photos with various settings for about ten to fifteen minutes.  I took a few minutes to just look around at the night sky from this location, liking the clear 360 degree visibility (lack of trees and less light pollution, if you didn’t look towards the church building).  I could clearly see the constellations Scorpius, Sagittarius, Cassiopeia, Ursa Major, but still only about half the stars in Ursa Minor.  I could not yet see Pegasus as it still needed another hour or two to rise out of the east.

I packed up the camera gear and headed home, using Eisenhower Road to get back to Lansing.  I parked the van, noting that Sean’s car still sat in the driveway.  I returned to the living room, unpaused the 49th Parallel and again attempted to finish the film.  Within five minutes, Terry and Sean came upstairs and Sean said his goodbyes.  I asked Terry if he had even noticed that I’d been gone for an hour.  He had that ‘deer in the headlights’ look that answered my question well enough. 

I stopped my feeble attempt to finish the movie and instead switched to the season premiere of Top Gear, an episode featuring a battle between the three big American auto makers to produce a successor to the reigning but retiring police vehicle of choice:  the Ford Crown Victoria.  The Stig, driving a minivan, managed to evade all three Crown Vics, shaming the hosts (and the cars they were driving).  That initial segment ended in a free-for-all demolition derby of the retiring behemoths.  I made sure to Tweet the abuse to a friend who still owns (and loves) his Crown Victoria.

By the time we finished watching Top Gear, I realized I was up way past my bedtime.  I retreated upstairs and crashed. 

∞ ∞ ∞

I hit the snooze button a couple of times this morning, not happy at all with the shortened sleep.  I made a strong pot of Irish Blend tea to take with me during the morning commute so I wouldn’t nod off and disrupt my riders with an accident or off-road excursion.  I did remember to grab my camera’s memory card so I could download and review the photos I’d taken the previous evening. 

Mars Saturn Spica and Waxing Crescent Moon
Click photo for rest of album

I re-read the paragraph on the Astronomy.com web page and decided to test the equilateral triangle theory on my photos of Mars-Saturn-Spica.  I used a nice clear plastic ruler to measure, on my laptop screen, the distance in centimeters between the three corners of the triangle.  The distance between Saturn and Spica and Saturn and Mars appeared to be identical.  But the distance between Mars and Spica was greater by 1.5 to 2 centimeters.  So, technically, my photo did not confirm the observation of an imaginary equilateral triangle. Perhaps earlier in the day (or even the previous day), Mars might have been in the exact position to be equidistant visually from Saturn and Spica, but not last night at a quarter past nine o’clock. 

I still hope to net Neptune this weekend, but my chances are looking slim.  The weather forecast for the next few days includes thunderstorms.  Ironic, that, since my next night to volunteer at Powell Observatory is this coming Saturday.  This would be my third night of the public season, and if overcast, would make it two out of three times cloudy.

Teapot Steam

Star Party Sign In
Star Party Sign In (click image for rest of album)

My dad contacted me Thursday to coordinate conveyances for our weekend astronomical adventure, thinking we would be attending the monthly ASKC club meeting, but he was a week early. Since I had mentioned earlier in the week a desire to see the glorious summer spread of our own Milky Way Galaxy, he had called me several times the past few days to see about driving to northern Atchison county to escape the Kansas City area light pollution. Both Wednesday and Thursday evenings turned out to be hazy and cloudy, so we nixed the road trip north.

Instead, I suggested we attend the monthly star party at Powell Observatory.  I received two confirmation e-mails from David Hudgins, the club’s star party coordinator extraordinaire.  I decided to leave my scope at home because you don’t really need a scope to take in the Milky Way Galaxy.  If the skies grew dark enough, it would stretch from the southern horizon, up over the top, clear to the northern one.

I thought perhaps I was reliving last Friday (that would be the 13th) because when I got home early (by ten minutes) I walked into some surreal drama.  I won’t go into the stressful week at work (we’ve all had weeks like that), but I looked forward to forgetting work and ignoring the excessive heat by reading books and watching movies in a quiet, air conditioned home with my hubby and two Rotties.  I came home to find our satellite on the fritz and Terry needing me to pickup a prescription before the pharmacy closed at seven.  While he cooked dinner, I did some preliminary troubleshooting of the satellite system with little success and decided to call DirecTV customer service, knowing I’d probably be on hold for several minutes.  The technician wanted us to disconnect, check and reconnect all of our cables, which seemed a ridiculous request since the cable runs are static and have not been touched, moved or manipulated in years.  After almost ruining supper in an effort to jump through DirecTV tech support hoops, we hung up on them and sat down to eat.

By now, I had less than an hour to pickup the prescription, so I grabbed my purse and drove to the store.  I got as far as the pharmacy counter, where the assistant recognized me and had the prescription ready for me, but when I opened my purse, my billfold was missing.  I had left it in the van because I stopped at Starbucks after work for a mocha frappacino treat for the drive home.  Now I had to return home for my billfold and repeat the trip back to the pharmacy, a wasted trip, time and gas.  When I returned home the third time, Terry had solved the satellite system glich.  With our excessive heat and drought conditions, the ground supporting our satellite dish pole has dried up so far down into the ground, that the pole can now be easily moved back and forth and twisted on it’s concrete base.  One of our dogs could have bumped into it and messed up the alignment.  Terry used the signal strength meter diagnostics channel on the satellite receiver to dial the dish back in.

Hoping that would be the final challenge of the week solved for the moment, I called Dad just after seven o’clock and told him to head my way.  I gathered up my camera equipment, my pocket star atlas, a large hardcover edition of Backyard Astronomy (to review Milky Way info), my purse (with billfold) and a lidded glass of cool water.  I asked Dad to drive this weekend, volunteering to drive next weekend for the July club meeting.  The hour jaunt to Louisburg passed quickly and we arrived at Powell just moments after sunset.  The evening cooled off nicely, but remained calm, clear and surprisingly dry.  In fact, we experienced no dew (the bane of telescope optics) until after midnight.

Sterling Scope
Mike Sterling collimating his telescope while my dad attends.

Several club members were already present and setting up their scopes in the East Observing Field (click photo above for photos taken upon our arrival).  One member, Mike Sterling, introduced himself to me (asking if I was ‘the’ Jon Moss … apparently my name is known, if not my face or gender, from my blogging).  He was in the process of collimating his 20-inch Dobsonian.  My dad provided an extra pair of eyes to help finish.  Mike also gave us a color brochure published by Astronomy magazine of the illustrated Messier catalog.  This will come in handy in the future when I really get serious about an observing award.

Star Party Theme: Star Charts
Star Party Theme: Star Charts/Atlases

The theme for this month’s star party centered around star charts and atlases.  David Hudgins setup a table displaying several popular and easy-to-use books, visual aids and posters.  I indicated to David I already owned the Sky & Telescope Pocket Sky Atlas and a smaller version of the wheel night sky star guide (the circular atlas resting on top of the poster in the upper left hand corner of the table shown in the photo above).

Dad and I wondered among the scopes, waiting for twilight to fade and the stars to emerge.  Saturn and Mars, along with Spica and Arcturus appeared very early and most of the scopes honed in on our ringed neighbor.  By 10:30 pm, the skies had darkened enough to begin hunting for some of the brighter Messier objects.  Mike graciously asked me (several times over the course of the evening) what I wanted to observe next.  I drew a blank every time because my goal had been to see the Milky Way, not any specific object viewable in a scope.   He obligingly filled in the blank by touring through clusters, nebulae and a galaxy found in the constellation Sagittarius, Scorpius, Hercules and Ursa Major.   I tweeted the objects as we found them so I would have a record of what we saw and when.

Coathanger
Brocchi’s Cluster, also known as the Coathanger: a conspicuous asterism easily seen with binoculars in the constellation Vulpecula (via Wikipedia)

My dad and I also used his binoculars just to see what we could see with them (as opposed to a scope).  The highlight of that side project included finding Brocchi’s Cluster (more commonly known by the asterism ‘the Coathanger’).  One of the other club members used the Summer Triangle as an aid to locating the Coathanger.  As stated in the Wikipedia article: “It is best found by slowly sweeping across the Milky Way along an imaginary line from the bright star Altair toward the even brighter star Vega. About one third of the way toward Vega, the Coathanger should be spotted easily against a darker region of the Milky Way. The asterism is best seen in July-August and north of 20° north latitude it is displayed upside down (as in the picture above) when it is at its highest point.”

* Update * (added after original publication):

I completely spaced out tweeting during the eleven o’clock hour.  During this time, Mike disconnected the Goto electronics on his telescope and set me to star hopping for objects near Sagittarius.  The first one he tested me with was finding two small globular clusters a small hop away from the gamma star in Sagittarius (the star the delineates the spout of the teapot).  If I could find these two clusters, Mike told me I should be able to see both of them at the same time in the eyepiece’s field of view.  After about five minutes, I spied a couple of small fuzzy balls, not as distinct as the surrounding background stars, but I thought they might be the clusters.  Mike confirmed I had found them by doing a ‘happy dance’ and sing-songing ‘she found them, she found them’ for all to hear.  The designations for these clusters are NGC 6522 and 6528.

Mike next set me to finding either M69 or M70 (also hanging out in Sagittarius, but in the bottom of the Teapot).  I glanced at his star chart and used his excellent Telrad finderscope (which had a nice large field of view and an easy-to-use red bullseye) to quickly locate one of the Messier objects (probably M69).  Again Mike did a happy dance and song.

Mike went looking for another globular cluster, this time between Sagittarius and Scorpius, designated as NGC 6380.  I found this one especially interesting because of it’s apparent close proximity to a star.

The third test proved my undoing.  Mike moved his scope to Antares in Scorpius and set me to finding M4.  I didn’t review his star chart and spent several minutes attempting to find it.  Eventually, I gave up and Mike located it.

Teapot Asterism (for Sagittarius constellation)
Teapot Asterism (for Sagittarius constellation)

Despite all the mesmerizing Messier distractions, I did succeed in observing the vast sweep of our Milky Way Galaxy.  I learned a couple of cool memory aids and bits of trivia about finding the ‘heart’ of the galaxy and the path it takes.  Cygnus, the swan constellation, also sometimes known as the ‘Northern Cross,’ flies along the Milky Way, pointing directly to the heart of the galaxy.  To find the Milky Way’s heart, locate the Teapot (an asterism for the constellation Sagittarius), visible along the southern horizon during July and August, and imagine steam rising from the spout.

I even attempted to photograph the Milky Way using my simple tripod and DSLR camera, but without an equitorial mount of some kind with a tracking system and the digital photo editing software (to stack multiple repetitive exposures), the best I could accomplish was a three or four second exposure (using ISO 800) and fiddling with the brightness/contrast after downloading:

Steaming Teapot
Steaming Teapot (tilted slightly so that the Milky Way
appears centered/parallel to the frame of the photo).

I also took photos of Cygnus swimming in the Milky Way, the Summer Triangle, the Big Dipper over the dome of the observatory and several of the southern horizon.  To see the entire album, click on the photo at the top of this blog.

Soon after 12:30 a.m., Dad and I thanked Mike Sterling for the guided tour of the summer sky.  We packed up our gear and drove the hour home, where I finally drifted off to sleep after two o’clock with visions of Messier objects dancing in my head.

Dad and I had a blast and my husband is now having second thoughts about  staying home last night.  Many thanks to David Hudgins, Mike Sterling and the other members of the Astronomical Society of Kansas City for throwing a fun mid-summer star party.

Winter Circled Moon and Leonine Mars

I valiantly kept myself awake past my pumpkin transformation time (usually half past nine o’clock on weeknights), reading an ebook on my Nook Color while Terry dozed through the UFC fights.  When I finally got within twenty pages of the end of my book, I put the ereader aside and checked the position of Mars from my front porch.  The waxing moon hung at about the one o’clock position in the sky almost hidden behind my house and Mars shown redly at about the ten o’clock position. I decided to setup the telescope in my driveway, even though all the street lights and house lights concentrated their glows more intensely on the east side of my property.

I opened the garage door and began transferring the telescope and accessories from the band room (behind the garage on the west side of the house) through the garage to the driveway.  I had put on a sweater but only had flip-flops on my feet (something I would come to regret an hour or so later).

In setting up my telescope, I made an error in the home position and failed two attempts at an easy alignment.  When I finally realized my mistake, after having run the motors up to and beyond the stops twice, I tried a third time, but the Autostar control device disconnected itself from the telescope and reset itself twice.  I gave up and finally just pointed the scope at Mars, shining brightly and sanguinely from the constellation Leo.

Two of the stars selected by the Autostar alignment program included Sirius, in the constellation Canis Major, and Capella, in the constellation Auriga, and both of these stars could be found in the Winter Circle.  The waxing moon enjoyed center-stage in the Winter Circle on a cold clear late winter night.

Once I got Mars in my sights, I tried various barlows and eyepieces, but could never quite get a good focus on it.  I could dimly and vaguely see the polar ice cap and Mars definitely had an orange-ish and pink-ish cast to it.

By this time, I could barely feel my toes, but I didn’t want to stop observing, so I turned the telescope farther eastward, looking for Saturn.  I found Spica in the constellation Virgo.  Saturn is just a short hop to the left of Spica.  I clearly saw the rings, but did not take the time to look for Titan or any of Saturn’s other moons.  I wanted to get my feet warmed up, so I shutdown the telescope, packed everything up and transported it back to the band room.

I may repeat this entire process tonight, but from a different location.  I will take a nap this afternoon to allow me to stay up past my pumpkin transformation point.

Oh, and I did get my feet warmed back up while finishing the last twenty pages of my ebook.