Determination of elements in dust depositions by using ICP-OES

Improvements of Autonomous of TUG - T60 Robotic Telescope
Murat Dindar*1, Murat Parmaksizoglu1, Saniye Dindar1
Hasan Esenoglu1, 2, Selcuk Helhel1, Halil Kirbiyik1
1
* TUBİTAK National Observatory, 07058 Antalya, Turkey
2
Istanbul University, Faculty of Sciences, Department of Astronomy and Space Sciences,
34119 Fatih, Istanbul, Turkey
Abstract
A robotic telescope is a telescope that can make observations without hands - on human control. Its
low level behavior is automatic and computer – controlled. Robotic telescopes usually run under the
control of a scheduler, which provides high – level control by selecting astronomical targets for
observation. TÜBİTAK (Scientific and Technological Research Council of Turkey) National
Observatory (TUG) - T60 Robotic Telescope is controlled by open-source OCAAS software, formally
named TALON. This study introduces the improvements on TALON software, new electronic and
mechanic designs. Those improvements were tested on the simulation environments (driver – motion
control card and the running TALON computer). The all improvements that have been made in T60
robotic telescope make it more stable for robotic mode and encourage for the new challenges and
projects at the future.
Key words: Astronomy, Robotic Telescope, TALON Software, VOEvent, ToO, GAIA
1. Introduction
Design concept of the robotic telescope system has been developed and implemented over the
last two decades. One of the earliest microcomputers based telescope control system was
introduced by the Indiana University group [1] followed by many investigators [2]. The
advantage of the computer-based robotic telescope system was discussed elsewhere for low
operating costs with high operating efficiency and high scientific productivity [3]. Some
demonstrations of scientific usage of the robotic telescope were described in [4-5]. The robotic
control design concept was developed further by applying internet access [6].
Gamma – ray bursts (GRBs) are flashes of gamma rays associated with extremely energetic
explosions that have been observed in distant galaxies. They are the brightest electromagnetic
events known to occur in the universe [7]. Bursts can last from then milliseconds to several
minutes. The initial burst is usually followed by a longer – lived afterglow emitted at longer
wavelengths (X ray, ultraviolet, optical, infrared, microwave and radio) [8]. Targets of
Opportunity (ToO) are astronomical objects undergoing unexpected or unpredictable transient
phenomena and which are proposed for observation. Because of the transient nature of the event
the observations are normally urgent and may require even an immediate intervention at the
telescope. ToO include objects that can be identified before the onset of such phenomena (e.g.
*Corresponding author: Address: TÜBİTAK National Observatory, 07058, Antalya TURKEY. E-mail address:
murat.dindar@tubitak.gov.tr, Phone: +902422278401/1029 Fax: +902422278400
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dwarf novae, X-ray binaries) as well as objects which cannot be identified in advance (e.g. novae,
supernovae, gamma-ray bursts) [9].
TUG - T60 Robotic Telescope is controlled by open – source OCAAS software, formally named
TALON. This study introduces the improvements on TALON software, new electronic and
mechanic designs. Those improvements were tested on the simulation environments (driver –
motion control card and the running TALON computer).
New design and software implementation including mirror cover have been integrated to
autonomous structure of the T60 perfectly. Thus, the external effects such as dust, heavy particles
(which can fall down from dome directly to the surface of the mirror; oil, metallic particles etc.)
will be avoided successfully and implemented design to T60 to catch the VOEvent messages and
make them suitable for the observation, especially for the GAIA alert in the future. Thus, the
autonomous character of the telescope is gone a step further.
The all improvements that have been made in T60 robotic telescope make it more stable for
robotic mode and encourage for the new challenges and projects at the future.
2. T60 System Description
T60 is controlled by TALON formerly called OCAAS software based on open source GNU/C
UNIX platform. The telescope can be operated on robotic mode and the observations are made as
object – oriented. The corresponding technical specifications are on the table 1. T60 robotic
telescope is able to survey the dynamic catalogs such as edb (environmental data book); response
for the gamma ray burst alerts and makes long - time observation projects.
Table 1. T60 technical specifications [10]
Model
Optical Class
Aperture
Focal Length
Focal Ratio
Resolving Capacity
Image Scale
Filter Wheel
Dome
OMI RC06
Ritchey-Chrétien
600 mm
6000 mm
f/10
0.19”
34”/mm
12
ASH-DOME, “R”
model 14’6” 100
sec/rev
2.1. Software
T60, telescope control software, TALON provides the users to control the telescope both manual
mode (by GUI) and robotic mode (batch mode). The users are able to prepare the observations by
using the TALON tools such as mksch, telsched. The software architecture based on the daemons
which are able to execute all the processes simultaneously.
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TALON has two main daemons, telrun and telescoped. The telrun daemon is responsible for
operating the schedule on robotic mode by sending appropriate command to telescope daemon
(telecoped). The telecoped is responsible for the control of the dome, focus, filter wheel and the
telescope axes by sending the low – level commands to the motion controllers (Fig. 1). The
specific motion controller type is designed to control telescope by CSI (Clear Sky Instute)
company. Therefore, it has specialized built functions for the telescope control. The motion
controller cards could be programmed by using those functions, so that feature gives the
developers hardware independent design to improve the telescope control.
Figure 1. T60 software architecture [11]
2.2. Hardware
The servo motors are used in order to control the axes RA, Dec, focus and filter. The single phase
AC motor is used in order to control the dome. All motors are controlled in “Closed – Loop” by
using the motor drivers and the motion controller cards. Every motion controller card is
independent and programmed for the distinct processes (Fig. 2). By taking advantage of the
programmability of the motion control cards, the new designs could be easily adopted the
telescoped control system. Therefore, the hardware architecture is open for the developments.
3. T60 Control System Developments
The TALON software handles all the control for the components of the telescope such as filter,
focus, RA/Dec axes (Fig. 3). TALON controls the position of the components of the telescope
according to schedule file in the robotic mode.
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The astronomical calculations are made in TALON and the raw encoders for the axes are sent the
control cards. The position of the focus of the secondary mirror could be calibrated up to inside
temperature of the dome. The schedule file could be prepared by using the mksched individually
by the observers and the telescope operator merges the individual schedules by using the telsched
tool within TALON. Therefore, the new design and improvements should be adapted to robotic
structure of the telescope. In the robotic mode telescope can go to the defined coordinates and
tracks on the object during the defined duration in the schedule.
Figure 2. T60 hardware architecture [11]
Some of the developments could be summarized as followings. The first design of the T60 dome
was controlled in open – loop and mostly controlled manually. The opening and closing
processes have been done time dependently. Therefore, the dome sometimes got stuck and
observations failed. While searching the solution, the bug which TALON software tried to open
the shutter in one time was detected, so if it fails to open the dome before observation starts, all
observation night will be lost. In order to solve the problems, the close – loop control has been
improved by designing a new electronic card and low – level software for the feedback.
The low level software for the CSI motion control card is simply check the feedback from the
limit switches of the dome – shutter, then the success result is returned to the TALON user
computer, if it fails to open the dome – shutter; it tries again and again until it opens the dome,
successfully.
The mechanic, electronic and software components of mirror cover were designed by TUG
engineers (Fig. 4). Node 0 for the control of RA axis is used to control the mirror cover as well.
Therefore, the new control program was written for the CSI motion control card.
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Figure 4. The mechanic and electronic design of mirror cover
For the new design, the new drop – down list is implemented to the TALON GUI in order to
control the telescope in manually. The main challenge was to make it work in robotic. In order to
achieve that, the new algorithm is implemented to adopt the mirror cover in existing system by
taking into account the extreme situation such as the weather alert. When the weather alert
happens, the closing sequence should be mirror cover and dome – shutter respectively. While
closing in any case, weather alert or normal closing at the dawn. While opening case, vice versa.
Node 0 is used for tracking as well, so the process for the mirror cover should be finished exactly,
before the observation starts. Otherwise, the processes (tracking and mirror cover movement) are
conflicted and the system will get stuck. The new attribute for the dome state is checked firstly
and if it opened clearly, and then the open command sent to node 0 for the mirror cover in
recursive functions.
Figure 3. Improvements on TALON GUI
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During T60 test observation, sometimes it was enough to open just upper shutter according to the
observed object. However, if the object is close to the horizon, it is required to open the lower
shutter manually first and then upper shutter respectively which consumes ten minutes of
observation time. On the other hand, it is not allowed in the schedule to shorten observation time
in order to get rid of ten minutes loss within observation. Therefore, the objects which exist 25
degree below of horizon are omitted from the schedule. Then, reverse of this procedure is carried
out at upcoming observation nights and, in turn, schedule is revised frequently to observe the
objects which are close to horizon by leaving the lower shutter open [11].
To avoid the ten minutes loss, the lower shutter cover is automated. On the hardware side, a
geared motor, limit switches, steel wire and double connecting rods are used. By adding some
improvements to the software, when the open command is received, lower shutter is opened and
with the usage of upper shutter’s limit switch which informs it is opened, then upper shutter starts
to open. After opening both shutter cover automatically, control software is informed (Fig. 5).
Figure 5. The mechanic and electronic design of the mirror cover
The new alert daemon program is written from scratch to catch the ToO events. The new
software uses the Global VOEvent Network (GVN) [12]. It listens the TCP/IP port for the
VOEvent messages in the XML format. The software is implemented in TALON software by
running with telrun daemon.
Telrun daemon is responsible to operate the astronomical schedule, when the alert rises, telrun
responses it and stops the regular schedule. The alert daemon determines whether the event is
observable or not; if it is, alerts parses the VOEvent XML messages to the alert.sls format which
is format that telrun operates (Fig. 6). Telrun operates the alert.sls file until the observation
completes. Then telrun operates the regular schedule.
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Figure 6. The algorithm of the alert daemon
Conclusions
Developments and improvements that have been achieved so far on T60 robotic telescope make it
more stable for the robotic mode, and encourage us for further improvements and future
challenges. The main advantage of TALON software is that it was implemented on open –
source GNU/C platform. Therefore, Using of the open – source software makes the system more
developing and progressive.
The existing control software is wholly dependent on the motion control card. So the next
challenge is that the universal platform could be developed by gaining experiences from
developments.
References
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