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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"

20960 results found.

  1. EP241217a: VLA Radio Detection

  2. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  3. GRB 241229B: Continued CrAO ZTSh observations
  4. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  5. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  6. GRB 241229A: EP-FXT X-ray afterglow confirmation
  7. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  8. EP241217A: J band upper limit by SYSU 80cm telescope
  9. GRB 241228B: SAO RAS optical observations
  10. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  11. GRB 241229A: SAO RAS optical observations
  12. GRB 241229B: SVOM/VT optical candidate
  13. GRB 241229A: Swift-XRT observations
  14. EP240702a: 7DT Optical upper limits
  15. GRB 240606B: 7DT Optical upper limits
  16. Fermi trigger No 757231333: Global MASTER-Net observations report
  17. GRB241229B: UVOT upper limits
  18. GRB 241228B: D50 optical detection
  19. GRB 241228B: Fermi GBM Observation
  20. GRB 241228B: Swift-XRT afterglow detection
  21. GRB 241229A: Swift ToO observations
  22. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  23. GRB 241228A: Mondy optical afterglow observations
  24. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  25. Swift GRB 241229B: Global MASTER-Net observations report
  26. GRB 241229A: GOTO optical upper limits
  27. GRB 241228A: NOT optical upper limits
  28. GRB 241228B: LCO optical observation
  29. Fermi GRB 241228B: Global MASTER-Net observations report
  30. GRB241228B: GROWTH-India Telescope optical observations
  31. Swift GRB 241228A: Global MASTER-Net observations report
  32. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  33. GRB 241228B: GOTO24jmz optical follow-up observations
  34. GRB 241228B: Swift ToO observations
  35. GRB 241228B: TRT optical counterpart confirmation
  36. GRB 241228A: Swift/UVOT Upper Limits
  37. GRB 241228B: GOTO possible optical counterpart candidate
  38. GRB 241217A/EP241217b: continued SOAR observations
  39. Fermi GRB 241226A: Global MASTER-Net observations report
  40. EP241223a: Mondy AZT-33IK optical observations
  41. GRB 241029A: LCO optical observation
  42. GRB 241223A: Swift-XRT observations
  43. GRB 241029A: AbAO AS-32 optical observations
  44. Fermi trigger No 756678579: Global MASTER-Net observations report
  45. IceCube Alert 241224.30: Global MASTER-Net observations report
  46. EP241223a: Global MASTER-Net observations report
  47. EP241223a: EP-WXT detection of a fast X-ray transient
  48. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  49. GRB241113A: 7DT Optical upper limits
  50. Fermi GRB 241223A: Global MASTER-Net observations report
  51. GRB 241223A: GOTO optical observations summary
  52. GRB 241105A: JWST photometric observations of the host galaxy
  53. GRB 241223A: Swift ToO observations
  54. EP241217a: e-MERLIN radio observations
  55. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  56. Fermi trigger No 756447119: Global MASTER-Net observations report
  57. Fermi GRB 241221A: Global MASTER-Net observations report
  58. EP241021a: VLA radio detection
  59. GRB 241218A: Mondy AZT-33IK optical upper limit
  60. EP241217a : Leavitt Observatory optical upper limit
  61. EP241217a: 1.6m Mephisto multi-band optical observations
  62. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  63. GRB 241218A: Swift/UVOT Upper Limits
  64. GRB 241218A: NOT optical upper limits
  65. EP 241217a: NIR detection with P200/WIRC
  66. EP 241217a: Possible J-band detection with WINTER
  67. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  68. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  69. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  70. GRB 241217A / EP241217b: NOT optical upper limits
  71. GRB 241218A: REM optical upper limit
  72. GRB 241217A/EP241217b: REM optical/NIR upper limits
  73. EP241217a: REM optical/NIR upper limits
  74. EP241217a: Liverpool Telescope optical follow-up
  75. EP241217a: NOT optical observations
  76. EP241217a: GROWTH-India Telescope optical observations
  77. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  78. EP241119a: 7DT Optical upper limits
  79. EP241217b: Global MASTER-Net observations report
  80. GRB 241209A: ATCA radio follow-up observations
  81. EP241217a: Xinglong optical follow-up observations
  82. EP241217a: Global MASTER-Net observations report
  83. GRB 241217A : SVOM/VT optical afterglow detection
  84. GRB 241217A: Swift-XRT afterglow detection
  85. GRB 241217A: GRANDMA/TAROT optical upperlimits
  86. EP241217a: Swift-XRT Detection
  87. EP241217A: Non-detection from Fermi-GBM Observations
  88. EP241217a: Gemini-North spectroscopic redshift z = 4.59
  89. EP241217a: Kinder optical follow-up observations
  90. EP241217A: LCO optical observations
  91. EP241217a: Gemini-North detection of the likely optical counterpart
  92. EP241217a: EP detection of an X-ray transient
  93. EP241107a: VLA Radio Observation
  94. GRB 241215A: Mondy AZT-33IK optical observations
  95. GRB 241212A: Swift-XRT observations
  96. GRB 241215A: Nanshan/HMT optical upper limit
  97. GRB 241215A: Montarrenti Observatory optical upper limit
  98. Integral GRB241215.58: Global MASTER-Net observations report
  99. GRB 241213B: Swift-XRT observations
  100. GRB 241213A: SVOM/VT optical candidate

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