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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

26363 results found.

  1. EP241021a: OHP/T193 further optical observations
  2. LIGO/Virgo/KAGRA S241102br: OHP/T193 optical observations
  3. LIGO/Virgo/KAGRA S241102cy: Updated Sky localization
  4. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  5. EP241103a: Swift XRT detection and improved X-ray position
  6. EP241021a: continued SOAR observations
  7. EP241101a: Optical upper limits with Kinder observations
  8. EP241101a: OHP/T193 optical observations
  9. LIGO/Virgo/KAGRA S241102br: MASTER observations and OT detection
  10. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  11. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  12. EP241103a: GSP optical upper limit
  13. EP241103A: LCO optical observations
  14. EP241103a: an X-ray transient detected by Einstein Probe
  15. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  16. S241102cy: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
  18. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  19. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  20. GRB241030A: OHP/T193 optical observations
  21. GRB 241101A: FRAM-ORM optical limit
  22. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  23. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  24. EP241021a: Upper limit from Konus-Wind observations
  25. GRB 241101A: Swift-BAT refined analysis
  26. GRB 241030A: further SAO RAS optical observations
  27. GRB 241030A: Optical Observations via Virtual Telescope Project
  28. EP241021a: Liverpool Telescope optical follow-up observations
  29. GRB 241030B: Swift-XRT refined Analysis
  30. GRB 241026A: SAO RAS optical observations
  31. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  32. GRB 241101A: Swift detection of a burst
  33. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  34. EP241021a: OHP/T193 optical observations
  35. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  36. GRB 241030B: Montarrenti Observatory optical upper limit
  37. EP241026b: Liverpool Telescope optical follow-up
  38. GRB 241030A: SAO RAS optical observations
  39. GRB 241030A: Fermi GBM Observation
  40. EP241021a: AMI-LA radio detection
  41. GRB 241030B : GIT optical upper limits
  42. GRB 241030B: LCOGT Optical Upper Limits
  43. GRB 241030B: Swift-BAT refined analysis
  44. GRB 241030A: Swift-BAT refined analysis
  45. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  46. GRB 241030B: Swift/UVOT Detection
  47. GRB 241029A: LCO optical detection
  48. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  49. GRB 241030B : MITSuME Akeno optical upper limits
  50. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  51. GRB 241030B: SVOM/VT optical afterglow observations
  52. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  53. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  54. GRB241030B: Fermi GBM Observation
  55. GRB 241030B: BTA observations
  56. GRB 241029A: SVOM/VT optical afterglow observations
  57. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  58. GRB 241030B: Enhanced Swift-XRT position
  59. GRB241030B: GRANDMA/TAROT Upper Limit
  60. GRB 241030A: Swift-XRT refined Analysis
  61. GRB 241030B: SAO RAS optical observations
  62. GRB 241030B: AKO Optical Afterglow Detection
  63. GRB 241030B: Nanshan/HMT optical afterglow detection
  64. GRB 241030B: Swift detection of a burst
  65. GRB 240912A: radio detection with the VLA
  66. GRB 241030A: AKO Optical Afterglow Detection
  67. GRB 241030A: Swift/UVOT Detection
  68. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  69. GRB 241026A: Swift-BAT refined analysis
  70. GRB 241030A: SVOM/C-GFT optical observations
  71. GRB 241026A: LBT optical observations
  72. EP241021a: Optical rebrightening observations with Mephisto
  73. GRB 241030A: Multiband optical detection with Mephisto
  74. GRB 241030A: SVOM/VT optical afterglow observations
  75. GRB 241030A : MITSuME Akeno optical afterglow detection
  76. GRB 241030A: Enhanced Swift-XRT position
  77. GRB 241029A: GROWTH-India Telescope optical follow up
  78. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  79. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  80. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  81. GRB 241029A: SAO RAS optical observations
  82. GRB 241026A: SAO RAS optical observations
  83. EP241021a: SAO RAS observations of rebrightening
  84. GRB 241029A: GTC/OSIRIS+ spectroscopic redshift z=1.072
  85. MISTRAL@OHP photometric and spectroscopic observations of GRB 241029A
  86. GRB 241026A: Swift/UVOT Upper Limits
  87. GRB 241029A: Swift-XRT observations
  88. GRB 241029A: Fermi GBM Observation
  89. GRB 241029A: AKO Optical Afterglow Detection
  90. EP241021a: continued SOAR observations confirm optical rebrightening
  91. GRB 241029A: Xinglong-2.16m optical afterglow confirmation
  92. GRB 241029A: Mephisto observations
  93. EP 241026b: LBT possible optical counterpart (brightening source)
  94. GRB 241029A: TRT optical afterglow candidate detection
  95. GRB 241026A: TNOT optical counterpart detection
  96. GRB 241025A (EP241025a): Optical afterglow observations with the Tsinghua-Nanshan Optical Telescope
  97. GRB 241025A: further SAO RAS optical observations
  98. GRB 241026A: BTA and Zeiss-1000 optical observations
  99. GRB 241026A: SVOM/GRM observation
  100. EP241026B: GROWTH-India Telescope optical upper limit

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