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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"

20967 results found.

  1. GRB 250101A: SVOM/C-GFT early optical observations
  2. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  3. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  4. GRB 250101A: Nanshan/HMT optical observations
  5. GRB 250101A : GIT optical detection
  6. Swift GRB250101.56: Global MASTER-Net observations report
  7. GRB 241217a/EP241217b: ATCA Radio Detection
  8. EP241217a: VLA Radio Detection

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

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