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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"

26362 results found.

  1. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  2. GRB 241229B: Swift-BAT refined analysis
  3. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  4. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  5. GRB241229B: UVOT upper limits
  6. GRB 241228B: Fermi GBM Observation
  7. GRB 241228B: Swift-XRT afterglow detection
  8. GRB 241229B: Fermi GBM Observation
  9. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  10. GRB 241228A: Mondy optical afterglow observations
  11. GRB 241229A: GOTO optical upper limits
  12. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  13. GRB 241228A: NOT optical upper limits
  14. GRB 241228B: LCO optical observation
  15. GRB 241228A: Swift-BAT refined analysis
  16. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  17. GRB 241228A: Fermi GBM Observation
  18. GRB241228B: GROWTH-India Telescope optical observations
  19. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  20. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  21. GRB 241228A: GROWTH-India telescope optical upper limit
  22. GRB 241228B: TRT optical counterpart confirmation
  23. GRB 241228A: Swift-XRT refined Analysis
  24. GRB 241228A: Swift/UVOT Upper Limits
  25. GRB 241228A: Enhanced Swift-XRT position
  26. GRB 241228A: Swift detection of a burst
  27. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  28. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  29. GRB 241212A: VZLUSAT-2 detection
  30. EP241223a: Mondy AZT-33IK optical observations
  31. GRB 241029A: LCO optical observation
  32. GRB 241223A: Swift-XRT observations
  33. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  34. GRB 241029A: AbAO AS-32 optical observations
  35. GRB 241223A: Fermi GBM Detection
  36. Fermi trigger No 756678579: Global MASTER-Net observations report
  37. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  38. EP241223a
  39. EP241223a: EP-WXT detection of a fast X-ray transient
  40. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  41. GRB241113A: 7DT Optical upper limits
  42. GRB 241223A: GOTO optical observations summary
  43. GRB 241105A: JWST photometric observations of the host galaxy
  44. EP241217a: e-MERLIN radio observations
  45. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  46. The EP-WXT trigger 01709129287 is likely a flaring star
  47. EP241217a: Liverpool Telescope optical upper limit
  48. EP241021a: VLA radio detection
  49. GRB 241218A: Mondy AZT-33IK optical upper limit
  50. EP241217a : Leavitt Observatory optical upper limit
  51. GRB 241217A/EP241217b: tentative VLT spectroscopic redshift z=1.879
  52. EP241217a: 1.6m Mephisto multi-band optical observations
  53. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  54. GRB 241218A: Swift/UVOT Upper Limits
  55. EP241217a: optical upper limit with the Liverpool Telescope
  56. GRB 241209B: EP-FXT afterglow detection
  57. GRB 241218A: NOT optical upper limits
  58. GRB 241218A: Swift-BAT refined analysis
  59. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  60. EP 241217a: NIR detection with P200/WIRC
  61. EP 241217a: Possible J-band detection with WINTER
  62. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  63. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  64. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  65. GRB 241217A / EP241217b: NOT optical upper limits
  66. GRB 241218A: REM optical upper limit
  67. GRB 241217A/EP241217b: REM optical/NIR upper limits
  68. EP241217a: REM optical/NIR upper limits
  69. GRB 241217a: Liverpool Telescope optical follow-up
  70. EP241217a: Liverpool Telescope optical follow-up
  71. GRB 241218A: Swift-XRT refined Analysis
  72. EP241217a: NOT optical observations
  73. EP241217a: GROWTH-India Telescope optical observations
  74. GRB 241218A: NUTTelA-TAO / BSTI Optical Limits
  75. EP241119a: 7DT Optical upper limits
  76. EP241217a: Xinglong optical follow-up observations
  77. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  78. GRB 241218A: LCOGT Optical Upper Limit
  79. GRB 241218A: Enhanced Swift-XRT position
  80. GRB 241217A: GMG Optical Upper Limit
  81. GRB 241218A: Swift detection of a burst
  82. GRB 241217A : SVOM/VT optical afterglow detection
  83. GRB 241217A: Swift-XRT afterglow detection
  84. GRB 241217A: LCO optical upper limit
  85. GRB 241217A: GRANDMA/TAROT optical upperlimits
  86. EP241217a: Swift-XRT Detection
  87. EP241217A: Non-detection from Fermi-GBM Observations
  88. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  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 241213A: Swift-BAT refined analysis
  95. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  96. GRB 241215A: Mondy AZT-33IK optical observations
  97. GRB 241212A: Swift-XRT observations
  98. GRB 241215A: Nanshan/HMT optical upper limit
  99. GRB 241215A: Montarrenti Observatory optical upper limit
  100. GRB 241215A: GROWTH-India telescope optical upper limit

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