ForHosting KIT · Developer Utilities

Solar declination by day of year

Solar declination is the angular distance of the Sun north or south of the celestial equator—the quantity that drives seasonal day length, solar altitude at noon, and simple irradiance models used in architecture, HVAC, and introductory astronomy.

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Run — free How it works & API

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Given only the day of the year as an integer from one through three hundred sixty-six, the standard cosine seasonal model returns an approximate declination in degrees without ephemerides, leap-second tables, or network calls: δ equals 23.45 degrees times the cosine of two pi over three hundred sixty-five times day minus one hundred seventy-two. Day one hundred seventy-two sits near the northern summer solstice so the cosine peaks near plus twenty-three point four five degrees; winter days produce negative values of similar magnitude. This capability evaluates that expression deterministically, rejects days outside one to three hundred sixty-six with a clear invalid input error, and returns structured JSON that homework checkers, solar-design spreadsheets, and lightweight astronomy pipelines can pin in continuous integration. The browser widget runs free on your device; the prepaid API charges $0.002 per successful item when servers and SDKs need the same contract.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

How do I use this capability?

Complete the fields above and run it on this page. The form highlights anything that needs attention.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/astro/solar-declination-day

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/astro/solar-declination-day \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"day":172}'

const res = await fetch("https://api.kit.forhosting.com/astro/solar-declination-day", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "day": 172
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/astro/solar-declination-day",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "day": 172
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/astro/solar-declination-day", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"day":172}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"day":172}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/astro/solar-declination-day", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "day": 172
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "astro.solar_declination_day",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →