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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"

32531 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. EP241103a: GOTO optical upper limit
  5. LIGO/Virgo/KAGRA S241102br: Updated Sky localization
  6. EP241101a: Possible detection of an optical counterpart with FTW
  7. EP241103a: Swift XRT detection and improved X-ray position
  8. EP241021a: continued SOAR observations
  9. EP241101a: Optical upper limits with Kinder observations
  10. EP241101a: OHP/T193 optical observations
  11. EP241103a: Gemini optical limits
  12. EP241103a: EP observation update
  13. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  14. GRB 241030A: Swift-UVOT observations of the optical prompt flare
  15. EP241103a: GSP optical upper limit
  16. EP241103A: LCO optical observations
  17. EP241103a: Global MASTER-Net observations report
  18. GRB 241030A: Rapid release of TESS data.
  19. EP241101a: Global MASTER-Net observations report
  20. GRB 241029A: GRBAlpha detection
  21. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  22. S241102cy: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  24. Kinder optical follow-up observations of EP241021a, EP241026b, and EP241030a/GRB241030A
  25. GRB241030A: OHP/T193 optical observations
  26. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  27. Swift GRB 241101A: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  29. GRB 241030A/EP241030a: TNOT observations of the optical counterpart
  30. EP241021a: Upper limit from Konus-Wind observations
  31. GRB 241101A: Swift-BAT refined analysis
  32. GRB 241030A: further SAO RAS optical observations
  33. GRB 241030A: Optical Observations via Virtual Telescope Project
  34. EP241021a: Liverpool Telescope optical follow-up observations
  35. GRB 241026A: SAO RAS optical observations
  36. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  37. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  38. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits (duplicate submission of 38023)
  39. GRB 241030B: NUTTelA-TAO / BSTI Optical Limits
  40. EP241021a: OHP/T193 optical observations
  41. GRB 241030A: Palomar 1-m telescope COSMOS optical observations
  42. GRB 241030B: Montarrenti Observatory optical upper limit
  43. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  44. EP241026b: Liverpool Telescope optical follow-up
  45. GRB 241030A: SAO RAS optical observations
  46. GRB 241030A: Fermi GBM Observation
  47. EP241021a: AMI-LA radio detection
  48. GRB 241030B : GIT optical upper limits
  49. GRB 241030B: LCOGT Optical Upper Limits
  50. GRB 241030B: Swift-BAT refined analysis
  51. GRB 241030A: Swift-BAT refined analysis
  52. GRB 241029A: COLIBRI Detection of the Optical Counterpart
  53. GRB 241030B: Swift/UVOT Detection
  54. EP EP241030a: Global MASTER-Net observations report
  55. GRB 241029A: LCO optical detection
  56. GRB 241030B: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.82
  57. GRB 241030B: SVOM/GRM observation
  58. GRB 241030B : MITSuME Akeno optical upper limits
  59. GRB 241030A: COLIBRI Continuing Detection of the Afterglow
  60. GRB 241030B: SVOM/VT optical afterglow observations
  61. GRB 241030B: COLIBRÍ Upper Limits on the Optical Counterpart
  62. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  63. GRB241030B: Fermi GBM Observation
  64. GRB 241030B: BTA observations
  65. GRB 241029A: SVOM/VT optical afterglow observations
  66. GRB 241030A: detection of the bright optical counterpart in ATLAS forced photometry
  67. GRB 241030B: optical observations from the INAF Asiago Observatory
  68. EP241021a: Swift-UVOT detection
  69. GRB241030B: GRANDMA/TAROT Upper Limit
  70. GRB 241030B: SAO RAS optical observations
  71. GRB 241030B: AKO Optical Afterglow Detection
  72. GRB 241030B: Nanshan/HMT optical afterglow detection
  73. GRB 241030B: SVOM/ECLAIRs detection of a burst
  74. Konus-Wind detection of GRB 241030A
  75. GRB 241030A: Fermi-LAT detection
  76. GRB 240912A: radio detection with the VLA
  77. Fermi GRB 241030A: Global MASTER-Net observations report
  78. GRB 241030A: AKO Optical Afterglow Detection
  79. Swift GRB 241030A: Global MASTER-Net observations report
  80. GRB 241030A: Swift/UVOT Detection
  81. EP 241021a: further Swift-XRT observations and X-ray counterpart detection
  82. GRB 241030A: SVOM/GRM observation
  83. GRB 241026A: Swift-BAT refined analysis
  84. GRB 241030A: SVOM/C-GFT optical observations
  85. GRB 241026A: LBT optical observations
  86. EP241021a: Optical rebrightening observations with Mephisto
  87. EP241026b: EP-FXT follow-up observation
  88. GRB 241030A: Multiband optical detection with Mephisto
  89. GRB 241030A: SVOM/VT optical afterglow observations
  90. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  91. GRB 241030A : MITSuME Akeno optical afterglow detection
  92. GRB 241029A: GROWTH-India Telescope optical follow up
  93. GRB 241030A: TRT optical observations
  94. GRB 241030A: Keck/LRIS spectroscopic redshift z = 1.411
  95. GRB 241030A: ULL-ASTRO-MASTER detection of a bright optical counterpart with the LCOGT 40-cm telescope at McDonald Observatory
  96. GRB 241030A: COLIBRÍ Detection of the Bright Optical Counterpart
  97. GRB 241029A: SAO RAS optical observations
  98. GRB 241026A: SAO RAS optical observations
  99. EP240919a / GRB 240919A: ATCA Detection of Radio Counterpart
  100. EP241021a: SAO RAS observations of rebrightening

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